Baxter Diagnostics Inc. v. AVL Scientific Corp. (924 F. Supp. 994, 1996)

ORDER FOR JUDGMENT

GADBOIS, District Judge.

AVL Scientific Corp. (“AVL”) obtained a license to use an optical sensor device that measures the concentration of gases in the blood. It alleges that Baxter Diagnostics Inc. (“Baxter”) willfully infringed United States Patent No. 4,557,900 and United States Reissue Patent No. 31,879 (collectively, “the Lubbers patent”), which cover this device, by developing single- and double-layer optical blood gas sensor devices. In response, Baxter contends that the Liibbers patent is invalid. Alternatively, it contends that its sensor devices do not infringe the patent or are de minimis uses of the patented technology. This Court holds that the Liibbers patent is valid. Baxter’s single-layer sensor infringes it because it is not a de minimis use of the patented technology; however, this infringement was not willful. The double-layer sensor does not infringe the patent either literally or equivalently.

I. VALIDITY OF THE LÜBBERS PATENT

Baxter contends that the Liibbers reissue patent is invalid (1) because it was procured through inequitable conduct and (2) because claims in it are obvious.

A Inequitable Conduct Before the Patent And Trademark Office

Baxter’s first invalidity allegation is that the Liibbers applicants conducted themselves inequitably while their reissue application was pending. Specifically, it asserts that Gordon Peterson, one of the attorneys in charge of prosecuting the application, failed to disclose to the Patent and Trademark Office (“the PTO”) that a scientist who submitted declarations advocating the patentability of the Liibbers technology was an employee of a company that had a license to use the technology. It also asserts that the applicants failed to disclose material prior art. In light of all the circumstances, the applicants’ conduct was not so culpable that the patent should be invalidated.

1. Alleged Failure to Disclose Material Prior Art

Baxter alleges that the applicants did not disclose United States Patent No. 3,612,866 (“the Stevens patent”) and British Patent No. 1,190,583 (“the Bergman patent”) to the PTO even though this prior art was the focal point in the prosecution of the German counterpart of the Lubbers patent application, and the German patent examiner requested that the drafters of the German application discuss it in the text of that application.

a. History of Liibbers Patent Prosecution

A summary of the factual history of the Liibbers patent prosecution and the Liibbers technology-is helpful in understanding Baxter’s allegations.

i. Overview of Liibbers Sensor Technology

The Liibbers patent teaches an apparatus that measures the concentration of gases, such as carbon dioxide or oxygen, in a blood sample. A vessel holds the blood sample to be tested. Within the vessel, a silicone diffusion membrane that is selectively permeable by certain gases separates the analyte gas from the blood. If the analyte is carbon dioxide, it reacts with water sealingly embedded in the membrane, changing the pH of the water. The fluorescent indicating dye that is also sealingly embedded in the membrane detects this pH change. To determine the concentration of gas, a technician interrogates the dye with a monochromatic light and reads the wavelength of the light that the dye emits. The wavelength varies according to the pH change.

it. Liibbers Patent Prosecution Timeline

Max-Planck Institute (“Max-Planck”), the owner of the Liibbers technology, filed the Liibbers patent application in Germany in 1975. It issued as a patent in late 1979. Claiming priority of the German Liibbers patent application, Max-Planck filed the American Liibbers patent application in 1976. The application issued as a patent in 1977. Max-Planck filed a reissue application in the United States on January 8, 1979. This application issued as a patent on May 5, 1985.

iii. Importance of Bergman and Stevens Patents to German Prosecution

During the prosecution of the German application, Drágerwerk AG, a German company, filed an opposition, asserting that the Stevens and Bergman patents made the Liibbers technology unpatentable. It contended that the Stevens and Bergman patents teach an indicator “sealingly embedded” in a diffusion membrane and that a sealingly embedded indicator is an essential feature of some of the claims in the Liibbers application. Responding to the Drágerwerk opposition, Max-Planck narrowed some claims and deleted some claims. (Bxs. 1791 & 1792.)

The German patent office ultimately found that the Stevens and Bergman patents did not preclude the patentability of the Liibbers technology. (Ex. 1795.) It distinguished the patents on two grounds. First, it found that, unlike the indicators in the Stevens and Bergman references, the indicator in the Liibbers patent is sealingly embedded in an indicator space that is selectively permeable by the analyte:

While the fluorescent indicator is in contact with the entire measuring cell in case of the known measuring arrangements, individual, selectively determinable components only may penetrate into the indicator space in case of the subject matter of the application. Higher measuring accuracy is thus obtained.

(Id. at 6.) Second, it found that Liibbers’ idea of separating the indicating space from the light-measuring means improved upon the Stevens and Bergman patents:

[T]he fact that the indicator space is provided independently of the light-measuring means is to be deemed an advantage according to the application over the known arrangements. Owing to this fact it is, for instance, possible to have the place of measurement shifted into the blood vessels themselves.

(Id.) It emphasized that “[njeither alone nor in combination are these two particularities suggested by prior art.” (Id. at 7.) However, it told Max-Planck to discuss the Stevens and Bergman patents in the text of the application. (See id. at 9 (“The prior art according [the Stevens and Bergman references], which comes closest to the subject matter of the application ... w[as] incorporated into the introduction to the new specification.”).)

iv. History of United States Reissue Application

Shortly after adding the discussion of the Stevens and Bergman patents to its German application, Max-Planck filed a reissue application in the United States to broaden the claims in the original Liibbers patent. The reissue application did not list the Stevens and Bergman patents in its “References Cited” section. (Ex. 331.) However, Max-Planck submitted a copy of the German Liibbers patent that discloses and discusses the Stevens and Bergman patents. (Ex. 221 at A000658.) It did not provide an English translation of this discussion.

Gordon Peterson, the attorney handling the prosecution, did not know about the Stevens and Bergman references. (Testimony of Gordon Peterson, Trial Tr. at 3314:6-10.) He had access to the German Liibbers patent, but he never obtained a translation of the portion of that patent which discusses them. (Id. at 3326:17-25; Testimony of Harry Weissenberger, Trial Tr. at 3213:9-12.)

However, several other individuals involved in the American prosecution had actual knowledge of the Stevens and Bergman references. AVL became involved in the prosecution after it became an exclusive licensee under the Liibbers patent. Dr. Hermann Marsoner and Dr. H.W. Kroneis, who worked for AVL and who were frequently consulted about the prosecution, published a paper that cited the references in 1983. (Ex. 4195 at 592.) In October 1981, Marsoner and Kroneis of AVL, Dr. .Dietrich Liibbers and Dr. Norbert Optiz of Max-Planck, and Dr. Harold Heitzmann of Cardiovascular Devices, Inc., a Liibbers licensee, attended a meeting at AVL. The minutes of the meeting show that they discussed the Stevens patent. (Ex. 387.) All of these scientists were actively involved in the prosecution of the reissue application.

They had many opportunities to inform Peterson and the PTO about the Stevens and Bergman references. He sent every PTO action and response to the scientists and to Dr. Hans Hofman, the agent who prosecuted the German patent. Many of his responses argued that the prior art did not teach sealingly embedding an indicating substance in a diffusion membrane. Liibbers and Hofinan commented on these responses. But neither they nor the other scientists informed Peterson of the Stevens and Bergman references.

Liibbers and Opitz were aware of their duty to disclose material prior art to the patent office. They had originally filed declarations with the PTO that did not contain an acknowledgement of their duty as inventors to disclose material prior art. (Ex. 211 at A000529, A00486-87.) The examiner notified them that them declarations were defective and asked that they file new declarations that acknowledged their duty to disclose. (Id. at A000529.) They complied with this request. The other scientists had been involved in prosecutions of patents on technology they had invented, so they were aware of the inventor’s duty to disclose material prior art to the PTO.

b. Law Governing Failure to Disclose Prior Art

“The concept of inequitable conduct in patent procurement derives from the equitable doctrine of unclean hands: that a person who obtains a patent by intentionally misleading the PTO cannot enforce the patent.” Demaco Corp. v. F. Von Langsdorff Licensing Ltd., 851 F.2d 1387, 1394 (Fed. Cir.), cert. denied, 488 U.S. 956, 109 S.Ct. 395, 102 L.Ed.2d 383 (1988). “Inequitable conduct requires proof by clear and convincing evidence.” Manville Sales Corp. v. Paramount Sys., Inc., 917 F.2d 544, 551 (Fed. Cir.1990). The party alleging invalidity must make a threshold showing that (1) the applicant or a person substantially involved in the preparation of the application withheld or misrepresented material information and (2) the applicant or a person substantially involved in the preparation of the application intended to deceive the PTO by withholding or misrepresenting the information. Halli burton Co. v. Schlumberger Technology Corp., 925 F.2d 1435, 1439 (Fed.Cir.1991); see also 37 C.F.R. § 1.56; Fox Indus, v. Structural Preservation Sys., 922 F.2d 801, 804 (Fed.Cir.1990) (stating that the duty of candor rests on the inventor and every other individual who is substantially involved in the preparation or prosecution of the application). If the party with the burden of proof makes these threshold showings, the court must balance materiality and intent: “The more material the omission, the less culpable the intent required, and vice versa.” Halliburton Co., 925 F.2d at 1439; Manville Sales Corp., 917 F.2d at 551. After receiving this evidence, the court must make an “equitable judgment” about whether “in light of all. the particular circumstances, the conduct of the patentee is so culpable that its patent should not be enforced.” LaBounty Mfg., Inc. v. United States Int’l Trade Comm’n, 958 F.2d 1066, 1070 (Fed.Cir.1992).

Information is material if there is a substantial likelihood that the patent examiner would have considered the omitted information important in deciding whether to allow the application to issue as a patent. 37 C.F.R. § 1.56; Fox Indus., 922 F.2d at 803. However, an applicant does not have to disclose “an otherwise material reference if the reference is cumulative or less material than those already before the examiner.” Halliburton Co., 925 F.2d at 1440.

“Direct proof of [intent to mislead] is rarely available but may be inferred from clear and convincing evidence of the surrounding circumstances.” LaBounty Mfg., 958 F.2d at 1076. Proof of gross negligence can be circumstantial evidence of an intent to mislead. Hewlett-Packard Co. v. Bausch & Lomb Inc., 882 F.2d 1556, 1562 (Fed.Cir. 1989). However, “the label ‘gross negligence’ covers too wide a range of culpable conduct to create such an inference in all eases.” Id. Instead, “[s]uch an inference depends upon the totality of the circumstances, including the nature and level of culpability of the conduct and the absence or presence of affirmative evidence of good faith.” Id.

The failure to disclose prior art references that invalidated claims in patent applications pending in foreign countries is strong evidence of intent to mislead. J.P. Stevens & Co. v. Lex Tex Ltd., 747 F.2d 1553, 1566 (Fed.Cir.1984). However, filing supporting documents that list the references “does not support a conclusion of intentional withholding.” Demaco Corp., 851 F.2d at 1396. For example, in Demaco Corp., the patent applicant failed to file a material prior art reference. However, the reference “was listed in the German priority document filed with the PTO” and was part of the file wrapper. Id. The Demaco court found that the presence of the reference in the file wrapper negated a finding of deliberate concealment.

c. Application of Law to Failure to Disclose Stevens and Bergman References

Although Baxter has proven by dear and convincing evidence that the Stevens and Bergman references are material, it has not proven that the Lubbers applicants intended to mislead the PTO. Thus, the applicants’ failure to disclose prior art does not render the Liibbers patent invalid.

i. Materiality of Stevens and Bergman References ■

There is a substantial likelihood that the patent examiner would have considered the Stevens and Bergman patents important in deciding whether to allow the Liibbers application to issue as a patent. Therefore, these references are material.

The German patent office stated that these references were the most pertinent prior art references it examined in conjunction with the Liibbers patent. (Ex. 1795 at 9.) Clearly, it believed that the references were important even though it ultimately decided that they did not preclude the patentability of the Liibbers technology. The initial German application and the application before the PTO were virtually identical. Arguably, the PTO was likely to agree with the German examiner and to find that the Liibbers claims were valid; however, references that were important to the German office would be important in appraising its work and would allow the PTO to make an independent decision about claim validity.

ii. Intent to Mislead

Although the Stevens and Bergman references are material, the applicants did not intend to deceive the PTO by withholding them. The presence of the references in the file wrapper, albeit not in the “References Cited” section of the application, demonstrates that the applicants were not actively hiding them from the PTO and did not intend to mislead it. See Demaco Corp., 851 F.2d at 4396. Furthermore, although the scientists who were active in helping Peterson with the prosecution had ample opportunity to suggest that he include the references in the “References Cited” section, given the German patent office’s determination that the Liibbers technology was patentable over the references, they thought that including the references was unnecessary. A belief that the PTO did not need the references to assess the Liibbers application accurately is not tantamount to an intent to mislead it by withholding information the applicant believes would result in an adverse decision.

iii. Balancing of Materiality and Intent

Balancing materiality and intent to deceive is improper in this case because Baxter has not made a threshold showing of an intent to deceive. See Halliburton Co., 925 F.2d at 1439. Nevertheless, the omitted references are not so material that they could offset the nonexistent intent to deceive. While the PTO was likely to have considered them important, they do not render claims in the patent invalid for obviousness. See infra Part I.B.3. The PTO would have issued the application as a patent even if it had known about the references. In light of the circumstances, the failure to list the Stevens and Bergman patents in the “References Cited” section of the application was not inequitable conduct that warrants invalidating the Liibbers patent.

2. Failure to Disclose Declarant’s Employment with Interested Party

Baxter’s other inequitable conduct allegation is that attorney Peterson failed to disclose that a scientist who submitted declarations supporting the Liibbers reissue application was an employee of a company that was a licensee under the Liibbers patent.

a. Peterson’s Submission of Interested Declaration

In April 1991, Peterson, who was representing Cardiovascular Devices, Inc., filed a protest to the Liibbers reissue application. (Ex. 209 at 74-80.) The protest does not reveal that Cardiovascular Devices is the protestor.

After filing this protest, Cardiovascular Devices obtained a license under the Liibbers patent from AVL. As a result, it began advocating the patentability of the Liibbers technology and became active in the prosecution of the reissue application. Peterson became the attorney responsible for handling the prosecution. (Testimony of Dr. John L. Gehrieh, Trial Tr. at 3224:18-21.)

When the patent examiner realized that Peterson had represented both the protestor and the applicants, he requested an explanation. (See Ex. 209 at 127 (stating that examiner had suggested that Peterson “file papers clarifying conflicting situation of being protesting attny [sic] and applicants’ attny [sic]”).) Peterson filed the requested explanation, stating that no conflict of interest existed because the protestor had obtained a license to use the Liibbers technology and had decided to withdraw the protest:

[A]fter filing the protest and upon further evaluation, the protestor took a license on a bundle of technology, including this reissue application. Thus, the former protestor is now a licensee and charged with the responsibility for prosecuting this reissue application. Protestor hereby formally withdraws its protest to the issuance of this reissue application. It can be seen, therefore, that there is no conflict because counsel has represented the same client throughout these proceedings and further because the protest has now been formally-withdrawn.

(Id. at 143-44.) He did not reveal the protestor’s identity.

Later in the prosecution, the PTO began, examining the issue of whether prior art disclosed using fluorescent dyes to detect carbon dioxide. It told Peterson that certain claims could issue if he could show that the dye phenol red does not fluoresce. (Ex. 211 at A000591.) To this end, he obtained a declaration from Dr. William Miller, a scientist who worked for Cardiovascular Devices. The declaration stated that phenol red could not be used as a fluorescent indicator in the device that the Lübbers patent describes. (Id. at [ AXXXXXX-XX ].) Both the declaration and a resume attached to the declaration disclose that Miller is an employee of Cardiovascular Devices. (Id. at A000593, A000596.) However, neither discloses that Cardiovascular Devices was the protestor turned licensee.

The Miller declaration did not sway the PTO, so Peterson arranged a telephonic conference between Miller and the patent examiner. (Id. at A000634.) He-also directed Miller to submit a supplemental declaration, explaining the factual basis for his conclusions about phenol red. (Id. at A000645.) The supplemental declaration does not reveal that Cardiovascular Devices was a Lübbers licensee. The interview and declaration apparently satisfied the PTO that phenol red could not fluoresce in the apparatus that the Lübbers patent describes.

b. Legal Standard Governing Duty to Disclose Declarant’s Bias

Neither the Manual of Patent Examining Procedure (“MPEP”) nor the Code of Federal Regulations affirmatively requires declarants to disclose their interest in a patent’s issuance. See 37 C.F.R. § 1.132; U.S. Department of Commerce, Patent and Trademark Office, Manual of Patent Examining Procedure.

However, the edition of the MPEP in use during the Lübbers prosecution stated that the PTO could consider the declarant’s interest when evaluating his declaration:

Affidavits or declarations should be scrutinized closely and the facts presented weighed with care. The affiant’s or declarant’s interest is a factor which may be considered, but the affidavit or declaration cannot be disregarded solely for that reason.

U.S. Department of Commerce, Patent and Trademark Office, Manual of Patent Examining Procedure § 716(3). The case law is consistent with the MPEP. The Federal Circuit’s predecessor held that an affidavit by an interested person is less persuasive than an affidavit by a disinterested person. In re McKenna, 203 F.2d 717, 720 (C.C.PA. 1953). However, the PTO may not disregard an affidavit solely because an interested person authored it. Id. Indeed, the affidavit “may be relied on when sufficiently convincing.” Id.; cf. Ashland Oil, Inc. v. Delta Resins & Refractories, Inc., 776 F.2d 281, 294 (Fed.Cir.1985), cert. denied, 475 U.S. 1017, 106 S.Ct. 1201, 89 L.Ed.2d 315 (1986) (holding that opinion testimony of a party with a direct interest in patent validity litigation is less persuasive than opinion testimony by a disinterested party but that the interested testimony could not be disregarded solely because it was interested).

Baxter contends that in order for the patent examiner to consider an applicant’s interest, the applicant must first disclose his interest. It argues that the case law and the MPEP effectively create a duty to disclose a declarant’s bias. No court has squarely addressed the issue.

This Court holds that the combination of Peterson’s duty of candor under Rule 56 of the Practice Rules in Patent Cases and section 716(8) of the MPEP created a duty to disclose Miller’s interest. Rule 56 provides:

A duty of candor and good faith toward the Patent and Trademark Office rests on ... each attorney ... who prepares or prosecutes the application____ All such individuals have a duty to disclose to the Office information they are aware of which is material to the examination of the application. Such information is material where there is a substantial likelihood that a reasonable examiner would consider it important in deciding whether to allow the application to issue as a patent.

37 C.F.R. § 1.56. There is a substantial likelihood that a patent examiner will consider a declarant’s interest important to the examination of the application because section 716(3) of the MPEP lists interest as a factor he may consider as he evaluates the contents of a declaration disputing the obviousness of a claim. The MPEP guides his work, so he is very likely to adhere to the section 716(3) factors when examining declarations even though these factors are advisory, not mandatory. His decisions about obviousness determine whether the application will issue as a patent.

c. Application of Law to Peterson’s Submission of Interested Declaration

While Baxter has made a threshold showing that Peterson intended to mislead the PTO and that the Miller declarations were material to the PTO’s decision to allow claims in the Lubbers patent, this Court makes the equitable judgment that, in light of all the particular circumstances, the conduct of the patentee and its attorney was not so culpable that the patent should be invalidated.

i. Peterson’s Intent to Deceive the PTO

The patent attorney’s duty to ensure that the declarant discloses his interest creates a presumption that unless an interest is disclosed, the declarant is disinterested. Peterson’s failure to see that Miller disclosed his interest misled the PTO because it presumed that Miller was disinterested. Thus, the declaration was deceptive. When patentees submit deceptive declarations, an inference of an intent to deceive arises from the “affirmative acts of submitting [the declarations], their misleading character, and the inability of the examiner to investigate the facts [set forth in the declarations].” Paragon Podiatry Lab., Inc. v. ELM Labs., Inc., 984 F.2d 1182, 1191 (Fed.Cir.1993). Neither Peterson nor Miller have stated “facts supporting a plausible justification or excuse for the misrepresentation.” Id.

ii. Materiality of Miller Declarations

The parties do not dispute that these declarations were material to the PTO’s decision to allow certain claims. The PTO stated that it needed to make a determination that phenol red would not fluoresce in the Liibbers apparatus before it could allow some of the claims to stand. (Ex. 221 at A000591.) The information in the declarations allowed it to make this determination.

iii. Equitable Judgment About Submission of Interested Declarations

Despite the threshold showings of materiality and intent to mislead, after evaluating the circumstances surrounding the Liibbers prosecution, this Court’s equitable judgment is that Peterson’s conduct was not so culpable that the patent should be invalidated. Baxter admits that the patent examiner did not expressly request that Peterson procure a disinterested declaration. (Testimony of Patrick Bright, Trial Tr. at 3488:7-10.)

Additionally, Peterson was not trying to dress faulty information in respectable clothes in order to fool the PTO. Baxter does not quibble with the content of the declarations and provides no evidence that suggests they were not scientifically sound. Its expert witness, Patrick Bright, stated that Miller did not lie about the properties of phenol red. (Id. at 3489:18-21.) Furthermore, it does not contend that the content of Miller’s declaration was scientifically inaccurate or that a disinterested witness would have disagreed with him. Instead, its expert witness merely speculates that if the patent examiner had been skeptical of Miller’s statement, the patent might not have issued. (Id. at 3444:16-11.)

Finally, the PTO could not have disregarded the Miller declarations solely because he was an interested person, and it could have relied on them if they were sufficiently convincing. If, as Baxter concedes, Miller’s statements are scientifically sound, the PTO would have found them sufficiently convincing. Invalidating the Lübbers patent because Miller did not disclose his affiliation with Cardiovascular Devices would be inequitable.

B. Obviousness of Lubbers Patent Claims

Baxter’s second invalidity allegation is that prior art renders claims 31-35 of the Lübbers patent obvious. In response, AVL argues that the patent describes a novel means for measuring the concentration of carbon dioxide in the blood. It asserts that no prior art teaches (1) a semi-permeable diffusion membrane that isolates carbon dioxide from other blood components; (2) a pH-sensitive fluorescent dye sealingly embedded in the membrane; and (3) using a fluorescent dye to measure the concentration of carbon dioxide.

1. Legal Standard Governing Obviousness

A patent claim is invalid “if the differences between the subject matter sought to be patented and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art to which said subject matter pertains.” 35 U.S.C. § 103. The party asserting obviousness must prove it by clear and convincing evidence. Bausch & Lomb, Inc. v. Barnes-Hind/Hydrocurve, Inc., 796 F.2d 443, 446 (Fed.Cir.1986), cert. denied, 484 U.S. 823, 108 S.Ct. 85, 98 L.Ed.2d 47 (1987).

In an obviousness analysis, the court must consider ‘“what the combined teachings of the references would have suggested to those of ordinary skill in the art.’ ” Cable Elec. Prods., Inc. v. Genmark, Inc., 770 F.2d 1015, 1025 (Fed.Cir.1985) (quoting In re Keller, 642 F.2d 413, 425 (C.C.P.A. 1981)). However, “[ojbviousness cannot be established by combining the teachings of the prior art to produce the claimed invention, absent some teaching, suggestion or incentive supporting the combination.” In re Geiger, 815 F.2d 686, 688 (Fed.Cir.1987).

Secondary considerations, such as evidence of commercial success or copying, may indicate obviousness or non-obviousness. Cable Elec. Prods., 770 F.2d at 1026-27. The party asserting non-obviousness has the burden of establishing a “ ‘nexus between the merits of the claimed invention and the evidence of secondary considerations____’” Id. at 1026 (quoting Simmons Fastener Corp. v. Illinois Tool Works, Inc., 739 F.2d 1573, 1575 (Fed.Cir.1984), cert. denied, 471 U.S. 1065, 105 S.Ct. 2138, 85 L.Ed.2d 496 (1985)).

a. Parties ’ Dispute Over Prior Art

Baxter argues that United States Patent No. 4,041,932 (“the Fostick patent”), United States Patent No. 3,114,610 (“the Gafford patent”), the Stevens patent, the Bergman patent, a 1928 article entitled “Volumetric Analysis Using UmbeUiferone as A Fluorescent Indicator” by Volmar and Widder, and an unpublished doctoral dissertation entitled “A Corrected Spectrofluorometer for Analysis of Turbid Media” by Boldt are prior art and render claims 31-35 obvious. AVL agrees that the Volmar and Widder article as well as the Fostick, Gafford, Stevens, and Bergman patents are prior art. However, it disputes the contention that the Boldt dissertation is prior art.

’ i. Overview of Boldt Dissertation

Dr. Michael Boldt presented his doctoral dissertation, “A Corrected Spectrofluorometer for Analysis of Turbid Media,” to Philipps University in Marburg, Germany in 1971. (Ex. 1801.) Dr. Liibbers supervised the preparation of the dissertation.

Baxter adduced hearsay testimony from its expert Donald Barbeau that the German Bibliothek Index states that the Philipps University Library had catalogued the dissertation by 1974. (Testimony of Donald Barbeau, Trial Tr. at 3350:18-3351:6.) He admits that he has not obtained affidavits from the library, explaining when it catalogued the dissertation. (Id. at 3361:21-25.) However, he obtained statements from library personnel who discussed when they catalogued the dissertation. (Id.)

it Legal Definition of Prior Art

Inventions that were “patented or described in a printed publication in this or a foreign country ... more than one year prior to the date of the application for the patent in the United States” are prior art. 35 U.S.C. § 102(b). “Because there are many ways in which a reference may be disseminated to the interested public, ‘public accessibility' has been called the touchstone in determining whether a reference constitutes a ‘printed publication.'" In re Hall, 781 F.2d 897, 899 (Fed.Cir.1986). A single catalogued doctoral dissertation is sufficiently accessible to one interested in the art to constitute a printed publication. Id. at 899-900; see also In re Cronyn, 890 F.2d 1158, 1160-61 (Fed.Cir.1989) (holding that three undergraduate student theses that were listed alphabetically by author on index cards in a shoebox in the chemistry department library at Reed College in Oregon were not catalogued in a meaningful way and were not prior art). “[C]ompetent evidence of the general library practice may be relied upon to establish an approximate time when a thesis became accessible.” Hall, 781 F.2d at 899.

Section 102 does not state the only sources of prior art. In re Font, 675 F.2d 297, 300-01 (C.C.P.A1982). An inventor’s admission that he “had actual knowledge of [a] prior ... invention constitutes an admission that it is prior art to” him. Id. at 301; see also Constant v. Advanced Micro-Devices, Inc., 848 F.2d 1560, 1570 (Fed.Cir. 1988) (holding that inventor who admitted reading an article before he conceived of his invention could not claim that the article was not prior art).

iit Application of Definition of Prior Art to the Boldt Dissertation

The Boldt dissertation is prior art. Barbeau’s hearsay about the Bibliothek Index is arguably incompetent evidence and therefore an unreliable basis for establishing the time when the dissertation was publicly available. However, as the professor supervising Boldt’s dissertation, Liibbers knew about Boldt’s scientific analysis and research by 1971 when he presented the dissertation to Philipps University. (See Ex. 1801 at 121 (thanking Liibbers “for the numerous discussions about the overall definition of the problem and for many valuable suggestions during construction of the spectrofluorometer”).)

Max-Planck filed the original American Liibbers patent application in 1976. Because Liibbers knew about the dissertation by 1971, more than a year before Max-Planck filed the application, it is prior art to him.

b. Parties’ Dispute Over Analogous Prior Art

A court may not use a prior art reference in an obviousness analysis unless it is analogous to the art at issue. Wang Labs., Inc. v. Toshiba Corp., 993 F.2d 858, 864 (Fed.Cir.1993). AVL argues that neither the Boldt dissertation nor the Volmar and Widder article is relevant prior art.

When determining whether prior art is analogous, a court follows a two-step inquiry: “(1) whether the art is from the same field of endeavor, regardless of the problem addressed, and (2) if the art is not within the same field of endeavor, whether it is still reasonably pertinent to the particular problem to be solved.” Id. at 864. “A reference is reasonably pertinent if, even though it may be in a different field from that of the inventor’s endeavor, it is one which, because of the matter with which it deals, logically would have commended itself to an inventor’s attention in considering his problem.” In re Clay, 966 F.2d 656, 659 (Fed.Cir.1992). To determine whether a reference would have logically come to an inventor’s attention, the court should analyze the invention’s purpose. “If a reference disclosure has the same purpose as the claimed invention, the reference relates to the same problem, and that fact supports the use of that reference in an obviousness rejection. An inventor may well have been motivated to consider the reference when making his invention.” Id. However, “[i]f it is directed to a different purpose, the inventor would accordingly have had less motivation or occasion to consider it.” Id.

i. Application of Definition to the Boldt Dissertation

The Boldt dissertation is analogous prior art because it is from the same field of endeavor as the Lübbers patent. The dissertation discusses using spectrofluorometers to measure redox potentials in turbid media. A spectrofluorometer is not a sensor. (Testimony of Dr. Otto Wolfbeis, Trial Tr. at 1811:16-17.) However, fluorometry is part of the optical sensor field. (Id. at 1812:9-12.)

ii. Application to the Volmar and Widder Article

The Volmar and Widder article, “Volumetric Analysis Using Umbelliferone As A Fluorescent Indicator,” is not analogous pri- or art. It is a two page discussion of the use of B methyl umbelliferone, a pH-sensitive dye, as a fluorescent indicator in alkalimetry and acidimetry. (Ex. 1748.) In layman’s terms, it describes the dye’s ability to measure the pH change in solutions. It notes that the dye was effective in measuring the pH change of a solution when carbonic acid was introduced. It does not, however, mention using the dye to detect gases.

Measuring the pH change in solutions is not the same field of endeavor as creating optical sensors, so the issue is whether the article is still reasonably pertinent to the particular problem that the Lübbers patent solves. The purpose of the article is to discuss a fluorescent dye that accurately reflects pH change in solutions. The purpose of the Lübbers invention is measuring the concentration of gases in a sample. These purposes are dissimilar. An inventor wishing to create a device that would accurately measure carbon dioxide in the blood is not likely to have considered an article that does not even mention gas detection. Therefore, the Volmar and Widder article is not analogous prior art.

2. Obviousness of Claims 31, 32, 34, and 35

Baxter argues that the Fostick patent, the Gafford patent, the Boldt dissertation, and the Volmar and Widder article make claims 31, 32, 34, and 35 obvious. Because the Volmar and Widder article is not analogous prior art, the Court will not consider it in the obviousness analysis.

a. Overview of Claims 31, 32, 34, and 35

Claims 31, 32, 34, and 35 are virtually identical. They describe a method and an apparatus for measuring the concentration of carbon dioxide in a sample. These claims are very similar to claims in the Fostick patent. However, that patent teaches a method for measuring oxygen concentration while the Lübbers patent teaches using a pH-sensitive fluorescent dye to detect both oxygen and carbon dioxide. Baxter contends that the Gafford patent and the Boldt dissertation make this alleged innovation obvious.

b. Description of Prior Art

i. Description of the Gafford Patent

The Gafford patent teaches a method for detecting carbon dioxide by using a pH-sensitive absorbance dye suspended in an aqueous solution. (Ex. 486.) Carbon dioxide reacts with the aqueous solution to form carbonic acid. The dye then reacts to this pH change. (Id. at col. 1, lines 61-68.) To measure the carbon dioxide concentration, a technician interrogates the dye with a light. The dye absorbs some of the light energy, lessening the intensity of the interrogating light. The degree of lessening varies according to the pH change. The technician measures the change in light intensity at the wavelength of the interrogating light. (Testimony of Glenn Enscoe, Trial Tr. at 2802:1-6.)

ii. Description of the Boldt Dissertation

The Boldt dissertation discusses a method for correcting spectrofluorometer data when this data is obtained from turbid media. In simplistic terms, turbid media is aMn to “cloudy water.” The dissertation argues that fluorometry is an advance over absorption spectrometry because it is more specific and sensitive. (Ex. 1801 at 6.) The thesis does not teach a method for obtaining accurate carbon dioxide measurements. Indeed, it does not mention carbon dioxide or any other gas. (Testimony of Donald Barbeau, Trial Tr. at 3420:14-20.)

c. Application of Prior Art to Claims 31, 32, 34, and 35

Baxter has argued an elaborate obviousness theory. It contends that the Fostiek patent mentions using infrared techniques to detect carbon dioxide. (Ex. 210 at col. 7, line 48 through col. 8, line 11.) The Gafford patent states that it improves upon infrared measurement techniques. (Ex. 486 at col. 1, lines 31-45.) It teaches using an absorbent dye to detect carbon dioxide after it passes through a semi-permeable membrane. The Boldt dissertation allegedly states an incentive for replacing an absorbent dye with a fluorescent dye when it notes that fluorescent indicators are more sensitive than absorbent indicators.

While there is a fairly clear incentive to combine the teachings of Fostiek and Gafford, the incentive to combine Fostiek, Gafford, and Boldt is much less compelling. Gafford specifically states that absorbent sensors are an improvement over the infrared techniques that Fostiek describes. However, while the Boldt dissertation notes that fluorometry is an improvement over absorbent spectrometry, it does not state that fluorescent dyes are more accurate than absorbent dyes in an optical sensor. A scientist reading the dissertation would not necessarily infer that a dye that works well in a fluorometer would work well in an optical sensor because a fluorometer is not a sensor. (Testimony of Dr. Otto Wolfbeis, Trial Tr. at 1811:16-17.) Indeed, the dissertation does not state that fluorescent 'dyes are superior indicators in all situations.

Other possible incentives to combine the references are missing. The dissertation does not discuss using fluorometry to detect gases, so someone reading it would not necessarily infer that fluorescent dyes are superior to absorbent dyes in detecting carbon dioxide or oxygen. Furthermore, it does not teach a semi-percneable membrane, which teaching could conceivably inspire a researcher to combine Gafford and Boldt.

The Boldt dissertation discusses an invention too disparate from the Lubbers technology to suggest or teach combining it with the Gafford and Fostiek references. The Court notes that Dr. Otto Wolfbeis, an expert testifying at trial, stated that combining the Boldt dissertation with the Gafford patent might be obvious to a modern-day optical sensor developer with twenty-twenty hindsight. However, the combination would not have been obvious when scientists, like Dr. Lubbers, first began developing the field of optical sensor technology. (Testimony of Dr. Otto Wolfbeis, Trial Tr. at 1812:13-19.)

3. Obviousness of Claim 33

Baxter also argues that the Fostiek, Stevens, and Bergman patents make claim 33 obvious. Except for the limitations that relate to sealingly embedding the indicator in a silicone membrane, claim 33 is virtually identical to the Fostick patent. Baxter contends that the Stevens and Bergman patents teach sealingly embedding the indicator in a silicone membrane. At first blush; the prior art seems to render claim 33 invalid for obviousness. However, construing the term “sealingly embedded” in the context of claim 33, demonstrates that its use is novel.

a. Overview of Stevens and Bergman Patents

The Stevens and Bergman patents teach mixing a fluorescent dye into a supporting matrix in order to detect oxygen in the blood. The Stevens patent states: “It will be readily understood that in the various embodiments above described, the transparent substrates employed to support the fluorescent material can be omitted if the fluorescent material is mixed with a suitably rigid transparent oxygen-permeable supporting matrix material, such as polyethylene or the like.” (Ex. 200 at col. 3, lines 30-35.) The Bergman patent states: “According to the present invention, a gas detector comprises a material capable of being excited to luminescence ... [and] a permeable or porous supporting matrix into which the excitable material has penetrated and been retained____” (Ex. 205 at p. 1, lines 25-34.)

b. General Definition of “Sealingly Embedded”

The Stevens and Bergman patents teach a general concept of sealingly embedding a dye when they discuss mixing fluorescent material with a matrix material. Taken out of context, “sealingly embedded” is “not a real specific type of term.” (Testimony of Dr. Harold Heitzmann, Trial Tr. at 2991:20.) Without any limitations or clarifying language, “sealingly embedded means ... that you have a construction of the sensor where the indicator dye is mixed in somehow in the layer with the semipermeable membrane.” (Id. at 2978:24-2979:1.) If claim 33 does no more than teach embedding a fluorescent dye in a membrane or matrix, it is invalid for obviousness.

c. Understanding “Sealingly Embedded” in the Context of the Liibbers Patent

Because the Liibbers technology detects blood gases other than oxygen, the term sealingly embedded necessarily means more than merely mixing a dye in a silicone membrane. Claim 33 is not invalid for obviousness.

Both the Stevens and Bergman patents employ a technique called fluorescence quenching. (Id. at 2987:16-19.) Essentially, “fluorescence quenching is the diminution in the fluorescence of the fluorophore caused by the intereaction of oxygen with that fluorophore.” (Id. at 2987:20-23.) The analyte oxygen molecules collide with the fluorophore. (Id. at 2988:1-3.) This collision causes the fluorophore to lose its energy. (Id. at 2988:7-11.)

The fluorescence quenching technique differs from detecting a blood gas like carbon dioxide with a pH-sensitive fluorescent dye, as the Liibbers patent teaches. The pH-sensitive fluorescent dye must be dissolved in water. (Id. at 2977:6-9; see also id. at 2991:21-25; Testimony of Dr. Otto Wolfbeis, Trial Tr. at 1807:8-12.) Carbon dioxide reacts with the water, creating carbonic acid and changing the pH of the water. (Testimony of Dr. Harold Heitzmann, Trial Tr. at 2988:16-20.) This difference in pH affects the pH-sensitive fluorescent dye. (Id.)

The Liibbers technology differs from the Bergman and Stevens technology because it involves a two-phase system. The pH-sensitive dye dissolved in water is the aqueous phase. (Id. at 2990:17-19.) The silicone matrix, in which the aqueous phase is sealingly embedded, is the solid phase. (Id.) The Bergman and Stevens patents involve only a single, solid phase because the dye is dissolved in the silicone. (Id. at 2990:20-2991:11.) The dye interacts with the oxygen, so an aqueous phase is unnecessary. (Id. at 2992:1-4.) “[L]ooking at either the Bergman or the Stevens patent, one would not know how to construct a sensor for carbon dioxide with a pH sensitive fluorescent dye.” (Id. at 2992:5-9.)

This explanation is consistent with the German patent office’s findings. It states that “the fluorescent indicator is in contact with the entire measuring cell” in the Stevens and Bergman technologies. (Ex. 1795 at 6.) In the fluorescence quenching technique used in the Stevens and Bergman patents, the oxygen interacts directly with the fluorescent dye, so a membrane that separates the indicating dye and the blood sample is unnecessary. (Testimony of Dr. Harold Heitzmann, Trial Tr. at 2988:21-25.)

In contrast the German patent office noted that “individual, selectively determinable components only may penetrate into the indicator space” in the Lübbers technology. (Ex. 1795 at 6.) In the two-phase system, a semi-permeable membrane is necessary to isolate the reaction between the carbon dioxide and the water from other blood elements. (Testimony of Dr. Otto Wolfbeis, Trial Tr. at 1819:7-15.) If the reaction were not isolated, a false pH reading would likely result.

Because the Lübbers patent states a novel two-phase detection apparatus, claim 33 is not invalid for obviousness.

4. Commercial Success of Lübbers Technology

AVL has argued that the commercial success of the Lübbers technology precludes a finding of obviousness. Even though prior art does not render the Lübbers patent invalid for obviousness, courts must always take evidence of secondary considerations into account, “ ‘not just when the decisionmaker remains in doubt after reviewing the art.’ ” Cable Elec. Prods., 770 F.2d at 1026 (quoting Stratoflex, Inc. v. Aeroquip Corp., 713 F.2d 1530, 1539 (Fed.Cir.1983)).

a. Commercial Use of Lübbers Technology

Cardiovascular Devices entered a license and technology transfer agreement with AVL in 1981. (Testimony of Dr. John L. Gehrieh, Trial Tr. at 3245:4-13.) Its primary goal in entering the agreement was to access the Lübbers technology. (Id. at 3261:9-14.) Employing this technology, it was able to develop its GasStat instrument, which was designed to measure blood gases and pH during open heart surgery. (Testimony of Dr. Harold Heitzmann, Trial Tr. at 2958:8-10.) It admits that the GasStat embodies elements of Lübbers patent claims. (Id. at 2965:19-21.)

When Cardiovascular Devices began selling the GasStat, it had to compete with the Oxy-Stat, an inexpensive instrument which allows doctors to measure the redness of blood in order to determine its oxygen content. (Id. at 3011:3-17.) Customers did not immediately switch to the more expensive, more technologically sophisticated GasStat (Id. at 3010:22-25.)

However, it eventually became a commercial success. (Id. at 3261:21-24.) Sales of the GasStat approached $20 million a year in 1991. (Testimony of Dr. Harold Heitzmann, Trial Tr. at 2966:5-8.) Indeed, “the GasStat played a major role” in Cardiovascular Device’s financial success. (Testimony of Dr. John L. Gehrieh, Trial Tr. at 3261:21-24.)

6. Law Governing Commercial Success Evidence

The party asserting non-obviousness must establish a nexus between commercial success and the merits of an invention. Cable Elec. Prods., 770 F.2d at 1027. This nexus is required because “for commercial success of a product embodying a claimed invention to have true relevance to the issue of nonobviousness, that success must be shown to have in some way been due to the nature of the claimed invention, as opposed to other economic and commercial factors unrelated to the technical quality of the patented subject matter.” Id.

Comparative, specific evidence, such as market share, growth of market share, or replacing earlier units sold by others, is necessary to establish commercial success. Kansas Jack, Inc. v. Kuhn, 719 F.2d 1144, 1151 (Fed.Cir.1983). Evidence consisting solely of the number of units sold cannot establish commercial success. Cable Elec. Prods., 770 F.2d at 1026-27; Kansas Jack, Inc., 719 F.2d at 1151.

c. Analysis of Commercial Success of GasStat

AVL has established a weak nexus between the commercial success of the GasStat and the merits of the Lübbers technology. It has not introduced any specific evidence about Cardiovascular Devices’ market share. However, it showed that the Oxy-Stat had been widely used and accepted when Cardiovascular Devices began marketing the GasStat. In order to garner any market share, it had to displace the Oxy-Stat. It eventually began replacing this device, and it gained a substantial market share.

This weak nexus between the commercial success of the GasStat and the merits of the Lübbers technology bolsters the finding that prior art does not render claims 31-35 of the Lübbers patent invalid.

II. INFRINGEMENT OF THE LUBBERS PATENT

Because Baxter has failed to establish that the Lübbers patent is invalid, the Court must examine AVL’s allegation that Baxter infringed it. Analysis of infringement claims proceeds in two phases. First, the court interprets the claims without reference to the accused device. SRI Int’l v. Matsushita Elec. Corp., 775 F.2d 1107, 1123 (Fed.Cir.1985) (en banc). Second, it compares the interpreted claims with the accused device to determine whether the device embodies, either literally or figuratively, each limitation specified in the claims. Smith-Kline Diagnostics, Inc. v. Helena Labs. Corp., 859 F.2d 878, 882 (Fed.Cir.1988). The patentee has the burden of proving infringement by a preponderance of the evidence. SRI Int’l, 775 F.2d at 1123.

A. Legal Standard for Claim Interpretation

Claim interpretation is a question of law. Markman v. Westview Instruments, Inc., — U.S. -, ---, 116 S.Ct. 1384, 1387-88, 134 L.Ed.2d 577. When interpreting claims, the district court begins by examining the claim language. North American Vaccine, Inc. v. American Cyanamid Co., 7 F.3d 1571, 1575 (Fed.Cir.1993), cert. denied, — U.S. -, 114 S.Ct. 1645, 128 L.Ed.2d 365 (1994). It should construe the language objectively, as “one skilled in the art would construe [it].” Smith-Kline Diagnostics, 859 F.2d at 882. Testimony by experts skilled in the art can elucidate the meaning of the claim terms. However, testimony by the patentor’s attorney “amounts to no more than legal opinion” and co-opts the “process of construction that the court must undertake”; therefore, “it is entitled to no deference.” Markman v. Westview Instruments, Inc., 52 F.3d 967, 983 (Fed.Cir.1995) aff'd, — U.S. -, 116 S.Ct. 1384, 134 L.Ed.2d 577.

If an inventor chooses to give a patent term a definition different from its ordinary meaning to one skilled in the art, “he must set out his uncommon definition in some manner within the patent disclosure.” Intellicall, Inc. v. Phonometrics, Inc., 952 F.2d 1384, 1388 (Fed.Cir.1992). Generally, when an inventor claims to have used an uncommon definition, the court examines the specification and patent history to interpret the term. Hormone Research Found., Inc. v. Genentech, Inc., 904 F.2d 1558, 1563 (Fed. Cir.1990), cert. dismissed, 499 U.S. 955, 111 S.Ct. 1434, 113 L.Ed.2d 485 (1991); Lear Siegler, Inc. v. Aeroquip Corp., 733 F.2d 881, 889 (Fed.Cir.1984) (“the place to [set forth an uncommon definition] is in the specification”).

1. Interpretation of Claims 31, 32, 34, and 35

a. Plain Language of Claims 31, 32, 34, and 35

The parties dispute the interpretation of claims 31-35 of the Lübbers patent. Claim 34 is an apparatus claim that specifies “an arrangement for measuring the concentration of carbon dioxide in a sample.” The elements of the claim are:

means for generating a light beam having a predetermined color characteristic;

indicating means for generating light signals from which the concentration of carbon dioxide in a sample to be measured can be determined, including

[2a] a light transmissive surface positioned to be impinged by said light beam,

[2b] a diffusion membrane adapted to be placed in proximity of a sample and being permeable to at least a carbon dioxide component thereof, and

[2e] an indicating substance that is capable of fluorescing positioned to be impinged by said light beam penetrating said light-transmissive surface and by said carbon dioxide component penetrating said diffusion membrane, said indicating substance responding when illuminated by said incident light beam by emitting a resultant light beam having an emitted component which has a color characteristic different from said predetermined color characteristic and is related to the concentration of carbon dioxide in the sample

means for conducting said resulting light beam away from said indicating substance through said light transmissive surface; and

means for discriminating said emitted component from said resultant light beam so that the change in the color characteristic of said indicating substance can be ascertained and

means for correlating the change in the color characteristic with the concentration of carbon dioxide in the sample.

(Ex. 331.) Claim 35 is dependent on claim 34 and merely adds the limitation: “[a] method as defined in claim 34 wherein said indicating substance includes a pH indicating substance.”

Claim 31 states “a method of measuring the concentration of carbon dioxide in a sample.” It is the method counterpart to apparatus claim 34. The elements of claim 34 are virtually identical to the elements of claim 31. Claim 32 is dependent on claim 31 and adds the limitation: “[a] method as defined in claim 31 wherein said indicating substance includes a pH indicating substance.”

b. Interpretation of Claim 34

Claims 31, 32, and 35 are dependent on or virtually identical to claim 34, so their interpretation is largely dependent on the interpretation of claim 34.

i. Definition of the Term “Indicating Substance”

The parties agree that the key to interpreting claim 34 is determining the definition of the term “indicating substance” and understanding the indicating substance’s role in the invention that the Lubbers patent describes. However, they dispute the meaning of the term “indicating substance.” AVL contends that the drafters of the Lübbers patent intended to give it an uncommon definition and argues that standing alone, it means nothing. Limitations in the claim define it. In response, Baxter asserts that the drafters did not give it an uncommon meaning, it has an inherent meaning apparent to one skilled in the art, and the “limitations” describe the role of the indicating substance in the invention instead of defining the term.

AVL has not identified where in the specification or patent history the Lübbers applicants set forth the uncommon definition. The Court has examined the specification, patent history, and plain language of the claims and cannot find an uncommon definition.

Because the specification, patent history, and claim language do not set forth an uncommon definition, the Lübbers applicants did not act as their own lexicographers and did not give the term “indicating substance” an uncommon meaning. Therefore, the Court must construe the term as one ordinarily skilled in the art would. At trial, expert witnesses testified that an indicating substance is a substance that responds to a chemical species by changing its optical properties. (Testimony of Dr. Otto Wolfbeis, Trial Tr. at 1785:16-20.) It “is the substance that undergoes a change in response to the environment.” (Testimony of Dr. Dennis Dougherty, Trial Tr. at 3064:14 — 24; see also Testimony of Dr. James Godsey, Trial Tr. at 886:5-11 (same).) This testimony comports with the dictionary definition of an “indicator,” which is “[a]n organic substance (usually a dye or intermediate) which indicates by a change in its color the presence or absence or concentration of some other substance, or the degree of reaction between two or more other substances.” Hawley’s Condensed Chemical Dictionary 634 (11th ed. 1987).

A substance is an element or compound that is homogenous. Id. at 1102. In a homogenous substance, “ ‘every part is like every other part.’ ” Id. (quoting Black & Conant, Practical Chemistry ). The term substance denotes a single compound; a scientist combining multiple compounds would not create a substance. See also Miles Labs., Inc. v. Shandon, Inc., 997 F.2d 870, 876 (Fed.Cir.1993), cert. denied, — U.S. -, 114 S.Ct. 943, 127 L.Ed.2d 232 (1994) (suggesting that using the singular form of a word, like “cabinet,” to describe an apparatus precludes the assertion that multiple units, like “cabinets,” literally infringe the claim).

ii. The Role of the Indicating Substance

Claim language explains the role of the indicating substance in the invention: (1) it must be capable of fluorescing; (2) it must be positioned to be impinged by a light beam with a predetermined color characteristic that has penetrated a light-transmissive surface; (3) it must be positioned to be impinged by a carbon dioxide component that has penetrated a diffusion membrane; and (4) when illuminated by the light beam, it must be capable of emitting a resultant light beam that has a color characteristic that is related to the concentration of carbon dioxide in the sample and that is different from the predetermined color characteristic of the illuminating light beam.

When an exciting light beam shines on an indicating substance that is capable of fluorescing, the indicating substance reacts “by emitting a new light component.” (Testimony of Dr. Dennis Dougherty, Trial Tr. at 3083:6-8.) The new light component has a longer wavelength than the exciting light beam. (Testimony of Dr. Otto Wolfbeis, Trial Tr. at 1777:12-18.)

The light beam that shines on the fluorescent indicator must have a predetermined color characteristic. In simplistic terms, “[f]luorescence measurement techniques ... involve directing light of one color onto a fluorescent indicator, which in turn, emits an output signal of another color. Thus, fluorescence creates a new color____” (Ex. 211 at A000474.) However, “color” is an imprecise term. (Testimony of Dr. Dennis Dougherty, Trial Tr. at 3084:23-25.) The experts construing this term testified that both the wavelength of the light and its intensity are color characteristics. (Id. at 3084:8-14; see also Ex. 331 at col. 5, lines 49-57 (stating that intensity is a color characteristic).) Thus, the exciting light beam has a predetermined wavelength and/or intensity. The new light component that the indicating substance emits must have a different wavelength and intensity.

Additionally, the indicating substance must be positioned to be impinged by both the exciting light beam and the analyte carbon dioxide. A substance is impinged by light or a gas when it is struck by them or when they collide with it. Webster’s New Collegiate Dictionary 575 (1973).

2. Interpretation of Claim 33

Claim 33 differs from claims 31, 32, 34, and 35 because it is not limited to carbon dioxide detection. Instead, it is an apparatus claim that teaches a device for measuring any type of gas in a sample.

a. Plain Language of Claim 33

Specifically, claim 33 describes “an arrangement for measuring the concentration of gases in a sample.” The elements of claim 33 are:

(1) a combination comprising means for generating a monochromatic light beam having a predetermined color characteristic

(2) indicating means for generating light signals indicative of the concentration of gases in a sample to be measured, including

(a) a light transmissive surface positioned to be impinged by said monochromatic light beam

(b) a diffusion membrane of silicone adapted to be placed in proximity of a sample and being permeable to a selected gas component thereof, and

(c) an indicating substance sealin