Prosecution Insights
Last updated: July 17, 2026
Application No. 19/127,207

METHODS AND SYSTEMS FOR DETECTING DIFFUSING SINGLE PARTICLES

Final Rejection §103
Filed
May 05, 2025
Priority
Nov 11, 2022 — provisional 63/424,642 +3 more
Examiner
FABIAN JR, ROBERTO
Art Unit
2877
Tech Center
2800 — Semiconductors & Electrical Systems
Assignee
Cambridge Enterprise Limited
OA Round
2 (Final)
71%
Grant Probability
Favorable
3-4
OA Rounds
1y 3m
Est. Remaining
96%
With Interview

Examiner Intelligence

Grants 71% — above average
71%
Career Allowance Rate
89 granted / 126 resolved
+2.6% vs TC avg
Strong +26% interview lift
Without
With
+25.5%
Interview Lift
resolved cases with interview
Typical timeline
2y 5m
Avg Prosecution
42 currently pending
Career history
178
Total Applications
across all art units

Statute-Specific Performance

§101
1.3%
-38.7% vs TC avg
§103
95.9%
+55.9% vs TC avg
§102
1.1%
-38.9% vs TC avg
§112
1.1%
-38.9% vs TC avg
Black line = Tech Center average estimate • Based on career data from 126 resolved cases

Office Action

§103
Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Response to Arguments Applicant’s arguments have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument. Claim Rejections - 35 USC § 103 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. Claim(s) 1, 2, 4, 11, 12, 13 is/are rejected under 35 U.S.C. 103 as being unpatentable over US10948397B2 (hereinafter Trichet) and in view of CN 110932084 A (hereinafter Li). Regarding claim 1, Trichet teaches a method for detecting diffusing particles, the method comprising: (a) introducing a sample comprising water (col 5 line 27) and a diffusing particle (fig. 1 element 8, col 6 lines 17-27, col 8 lines 28-33) to an optical microcavity (fig. 1 element 6, col 6 lines 13-16, col 6 lines 35-35-38), wherein the sample has a concentration of diffusing particles such that a probability of the diffusing particle occupying an optical mode volume is less than one (this limitation is based on para [0057] of the instant application; having a very low concentration; Trichet teaches this limitation, col 6 lines 24-27); (b) coupling probe light into the optical microcavity such that the probe light is in resonance with the optical microcavity (fig. 1 element 6, col 6 lines 13-16, col 6 lines 35-35-38), wherein the diffusing particle diffuses into the optical mode volume defined by the coupled probe light (col 6 lines 35-35-38); and (c) detecting output light from the optical microcavity as a function of time while maintaining resonance (col 17 lines 9-13). Trichet does not explicitly teach under conditions such that the optical microcavity experiences a photothermal nonlinearity and wherein the diffusing particle generates a change in the detected output light that is amplified due to the photothermal nonlinearity. Note that this limitation refers to para [0180] lines 1-9. Trichet teaches this limitation indirectly, as shown in fig. 5 n1-n4 are different indexes of refraction having nonlinearity values. Li, from the same field of endeavor as Trichet, teaches “under conditions such that the optical microcavity experiences a photothermal nonlinearity and wherein the diffusing particle generates a change in the detected output light that is amplified due to the photothermal nonlinearity” (this is explained p. 5 last two paragraphs; photo-thermal effect corresponds to the photothermal nonlinearity). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the invention to apply the teaching of Li to Trichet to have “under conditions such that the optical microcavity experiences a photothermal nonlinearity and wherein the diffusing particle generates a change in the detected output light that is amplified due to the photothermal nonlinearity” in order to have a device that is small in size, with simple preparation, and stable structure and flexible operation (Abstract lines 5-7). Regarding claim 2, Trichet teaches the method of claim 1, wherein the optical microcavity is an open-access optical microcavity (col 6 lines 4-6) configured such that a region of maximum intensity of the optical mode volume is accessible by the diffusing particle (col 5 lines 32-41, col 18 lines 27-32). Regarding claim 4, Trichet teaches the method of claim 1, wherein resonance in step (b) is associated with maximum transmission of the probe light through the optical microcavity (col 18 lines 27-32, col 18 lines 37-45) or minimum intensity of back-reflected probe light from the optical microcavity. Regarding claim 11, Trichet teaches the method of claim 1, wherein the detected output light is transmitted probe light comprising dips (this is shown in fig. 10, a dip 44 is formed, col 17 lines 22-29) or the detected output light is back-reflected probe light comprising spikes and the method further comprises measuring a temporal width of each of the dips (this is shown in fig. 10, graph shows as a function of time) or the spikes. Regarding claim 12, Trichet teaches the method of claim 11, further comprising generating a plot of intensity versus temporal width of each of the dips (this is fig. 10) or the spikes. Regarding claim 13, Trichet teaches the method of claim 1, wherein the detected output light is transmitted probe light comprising dips (this is fig. 10) or the detected output light is back-reflected probe light comprising spikes and the method further comprises measuring an autocorrelation function (ACF) from the dips (col 24 claim 23) or the spikes and calculating a hydrodynamic radius from the measured ACF (col 21 lines 29-41; also Gourley teaches calculating a hydrodynamic radius from the measured ACF, fig. 3 and col 19 eqn. 16). Claim(s) 3 is/are rejected under 35 U.S.C. 103 as being unpatentable over Trichet and Li as applied to claim(s) 1, 8 above, and in view of US9063117B2 (hereinafter Gourley). Regarding claim 3, Trichet does not teach the method of claim 1, wherein the optical microcavity is a Fabry-Perot microcavity having a cavity, wherein the optical mode volume is defined within the cavity. Gourley, from the same field of endeavor as Trichet, teaches the method of claim 1, wherein the optical microcavity is a Fabry-Perot microcavity having a cavity, wherein the optical mode volume is defined within the cavity (col 24 lines 10-14). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the invention to apply the teaching of Gourley to Trichet to have the method of claim 1, wherein the optical microcavity is a Fabry-Perot microcavity having a cavity, wherein the optical mode volume is defined within the cavity in order to make the device less costly (col 3 para 3). Claim(s) 5, 6, 7, 23 is/are rejected under 35 U.S.C. 103 as being unpatentable over Trichet and Li as applied to claim(s) 1 above, and in view of Saavedra, Carlos, et al. "A fiber Fabry-Perot cavity based spectroscopic gas sensor." arXiv preprint arXiv:2205.06835 (2022) (hereinafter Saavedra). Regarding claim 5, Trichet teaches the method of claim 4, “wherein maximum transmission of the probe light or minimum intensity of the back-reflected probe light, and the conditions in step (c) is obtained by coupling the probe light such that it undergoes constructive interference to form a standing wave within the optical microcavity” (col 8 lines 34-46, col 18 lines 37-46; the antinodes represent the constructive interference to form a standing wave within the optical microcavity). Trichet does not teach by adjusting one or more of: a power of the probe light, a gain of a Pound- Drever-Hall (PDH) servo loop coupled to a source of the probe light and the optical microcavity, and an offset of the PDH servo loop. Saavedra, from the same field of endeavor as Trichet, teaches by adjusting one or more of: a power of the probe light, a gain of a Pound- Drever-Hall (PDH) servo loop coupled to a source of the probe light and the optical microcavity (p. 4 col 2 para 3 lines 10-18; p. 4 col 2 para 3 lines 26-33), and an offset of the PDH servo loop (p. 4 col 2 para 3 lines 10-18; p. 4 col 2 para 3 lines 26-33). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the invention to apply the teaching of Goldsmith to Trichet to have by adjusting one or more of: a power of the probe light, a gain of a Pound- Drever-Hall (PDH) servo loop coupled to a source of the probe light and the optical microcavity, and an offset of the PDH servo loop in order to reduce noise background and a considerable increase of the measurement rate (p. 4 col 2 para 3 lines 10-18). Regarding claim 6, Trichet teaches the method of claim 5, wherein the standing wave is achieved by satisfying mʎ= 2nL, wherein m is an integer, ʎ is the probe light wavelength, n is the sample's refractive index, and L is the optical microcavity cavity length (the optical cavity 1 of fig. 1 follows mʎ= 2nL, see evidentiary reference CN106324727A p. 2 para 5). Regarding claim 7, Trichet teaches the method of claim 6 further comprising adjusting ʎ, adjusting L (col 11 lines 52-61), adjusting the power of the probe light, adjusting the gain of the PDH servo loop, adjusting the offset of the PDH servo loop, or a combination thereof to maintain resonance and the conditions in step (c). Regarding claim 23, the modified device of Trichet does not teach the method of claim 5, wherein the maximum transmission of the probe light or minimum intensity of the back-reflected probe light, and the conditions in step (c) are obtained by adjusting the offset of the PDH servo loop. Saavedra, from the same field of endeavor as Trichet, teaches the method of claim 5, wherein the maximum transmission of the probe light or minimum intensity of the back-reflected probe light, and the conditions in step (c) are obtained by adjusting the offset of the PDH servo loop (p. 4 col 2 para 3 lines 10-18). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the invention to apply the teaching of Saavedra to the modified device of Trichet to have the method of claim 5, wherein the maximum transmission of the probe light or minimum intensity of the back-reflected probe light, and the conditions in step (c) are obtained by adjusting the offset of the PDH servo loop in order to reduce noise background and a considerable increase of the measurement rate (p. 4 col 2 para 3 lines 10-18). Claim(s) 14, 15, 18, 19, 20, 21 is/are rejected under 35 U.S.C. 103 as being unpatentable over Trichet Li, and Saavedra. Regarding claim 14, Trichet teaches a system for detecting diffusing particles, the system comprising: (a) optoelectrical components configured to couple probe light into an optical microcavity such that the probe light is in resonance with the optical microcavity (the optoelectrical components are shown in fig. 8); (b) the optical microcavity to which a sample comprising water (col 5 line 27) and a diffusing particle is introduced to diffuse into an optical mode volume defined by the coupled probe light (this is shown in fig. 1), wherein the sample has a concentration of diffusing particles such that a probability of the diffusing particle occupying the optical mode volume is less than one (this limitation is based on para [0057] of the instant application; having a very low concentration; Trichet teaches this limitation, col 6 lines 24-27); (c) a detector configured to detect output light from the optical microcavity as a function of time (these are shown in fig. 8 element 28 and fig. 10); and (d) optoelectrical components configured to maintain resonance while using the detector to detect output light from the optical microcavity as a function of time (this is shown in fig. 10). Trichet does not teach wherein the optoelectrical components (d) provide a Pound-Drever-Hall (PDH) servo loop coupled to a source of the probe light and the optical microcavity, and the optical microcavity experiences a photothermal nonlinearity, and under the conditions such that changes in detected output light from the diffusing particle are amplified due to the photothermal nonlinearity. Li, from the same field of endeavor as Trichet, teaches “the optical microcavity experiences a photothermal nonlinearity, and under the conditions such that changes in detected output light from the diffusing particle are amplified due to the photothermal nonlinearity” (this is explained p. 5 last two paragraphs; photo-thermal effect corresponds to the photothermal nonlinearity). Note that this limitation refers to para [0180] lines 1-9. Trichet teaches this limitation indirectly, as shown in fig. 5 n1-n4 are different indexes of refraction having nonlinearity values. Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the invention to apply the teaching of Li to Trichet to have “the optical microcavity experiences a photothermal nonlinearity, and under the conditions such that changes in detected output light from the diffusing particle are amplified due to the photothermal nonlinearity” in order to have a device that is small in size, with simple preparation, and stable structure and flexible operation (Abstract lines 5-7). Trichet, when modified by Li, does not teach wherein the optoelectrical components (d) provide a Pound-Drever-Hall (PDH) servo loop coupled to a source of the probe light and the optical microcavity. Saavedra, from the same field of endeavor as Trichet, teaches wherein the optoelectrical components (d) provide a Pound-Drever-Hall (PDH) servo loop coupled to a source of the probe light and the optical microcavity (p. 4 col 2 para 3 lines 10-18; p. 4 col 2 para 3 lines 26-33). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the invention to apply the teaching of Saavedra to Trichet, when modified by Li, to have wherein the optoelectrical components (d) provide a Pound-Drever-Hall (PDH) servo loop coupled to a source of the probe light and the optical microcavity in order to reduce noise background and a considerable increase of the measurement rate (p. 4 col 2 para 3 lines 10-18). Regarding claim 15, Trichet teaches the system of claim 14, wherein the optical microcavity is an open-access optical microcavity (col 4 line 1) configured such that a region of maximum intensity of the optical mode volume is accessible by the diffusing particle (col 8 lines 34-46, col 18 lines 37-46; the antinodes represent the constructive interference to form a standing wave within the optical microcavity). Regarding claim 18, Trichet teaches the system of claim 14, further comprising a controller comprising a processor and a non-transitory computer-readable medium operably coupled to the processor, the non-transitory computer-readable medium comprising instructions, that, when executed by the processor, cause the controller to perform operations (col 12 lines 22-28) comprising: receiving a signal from the detector (fig. 1 element 28); “based on the received signal, coupling the probe light into the optical microcavity such that it undergoes constructive interference to form a standing wave within the optical microcavity” (this is fig. 5). Tichet fails to teach based on the received signal, adjusting one or more of a power of the probe light, a gain of the PDH servo loop, an offset of the PDH servo loop, or a combination thereof to maintain resonance and the conditions in (d). Saavedra, from the same field of endeavor as Trichet, teaches based on the received signal, adjusting one or more of a power of the probe light, a gain of the PDH servo loop, an offset of the PDH servo loop, or a combination thereof to maintain resonance and the conditions in (d) (p. 4 col 2 para 3 lines 10-18; p. 4 col 2 para 3 lines 26-33). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the invention to apply the teaching of Saavedra to Trichet to have based on the received signal, adjusting one or more of a power of the probe light, a gain of the PDH servo loop, an offset of the PDH servo loop, or a combination thereof to maintain resonance and the conditions in (d) in order to reduce noise background and a considerable increase of the measurement rate (p. 4 col 2 para 3 lines 10-18). Regarding claim 19, Trichet teaches the system of claim 14, further comprising a controller comprising a processor and a non-transitory computer-readable medium operably coupled to the processor, the non- transitory computer-readable medium comprising instructions, that, when executed by the processor, cause the controller to perform operations (col 12 lines 22-28) comprising: receiving a signal from the detector (fig. 1 element 28), “processing the signal to determine a temporal width for the signal; and outputting the determined temporal width” (this is shown in fig. 10). Regarding claim 20, Trichet teaches the system of claim 19, wherein the operations further comprise processing the signal to calculate a hydrodynamic radius of the diffusing particle and outputting the calculated hydrodynamic radius to the system (col 21 lines 29-41; also Gourley teaches calculating a hydrodynamic radius from the measured ACF, fig. 3 and col 19 eqn. 16). Regarding claim 21, Trichet teaches the system of claim 18, wherein the standing wave is achieved by satisfying mk = 2nL, wherein m is an integer, k is the probe light wavelength, n is the sample's refractive index, and L is the optical microcavity cavity length (the optical cavity 1 of fig. 1 follows mʎ= 2nL, see evidentiary reference CN106324727A p. 2 para 5). Regarding claim 24, the modified device of Trichet does not teach the system of claim 18, wherein the operations comprise adjusting the offset of the PDH servo loop to maintain resonance and the conditions in (d). Saavedra, from the same field of endeavor as Trichet, teaches the system of claim 18, wherein the operations comprise adjusting the offset of the PDH servo loop to maintain resonance and the conditions in (d) (p. 4 col 2 para 3 lines 10-18; p. 4 col 2 para 3 lines 26-33). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the invention to apply the teaching of Saavedra to the modified device of Trichet to have the system of claim 18, wherein the operations comprise adjusting the offset of the PDH servo loop to maintain resonance and the conditions in (d) in order to reduce noise background and a considerable increase of the measurement rate (p. 4 col 2 para 3 lines 10-18). Claim(s) 16 is/are rejected under 35 U.S.C. 103 as being unpatentable over Trichet, Li, and Saavedra as applied to claim(s) 14 above, and in further view of Gourley. Regarding claim 16, the modified apparatus of Trichet does not teach the system of claim 14, wherein the optical microcavity is a Fabry-Perot microcavity having a cavity, wherein the optical mode volume is defined within the cavity. Gourley, from the same field of endeavor as Trichet, teaches the system of claim 14, wherein the optical microcavity is a Fabry-Perot microcavity (col 24 lines 10-14) having a cavity, wherein the optical mode volume is defined within the cavity (col 24 lines 10-14, this is shown in fig. 15B the cavity is the channel 153). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the invention to apply the teaching of Gourley to the modified apparatus of Trichet to have the system of claim 14, wherein the optical microcavity is a Fabry-Perot microcavity having a cavity, wherein the optical mode volume is defined within the cavity in order to make the device less costly (col 3 para 3). Claim(s) 17 is/are rejected under 35 U.S.C. 103 as being unpatentable over Trichet, Li, and Saavedra as applied to claim(s) 14 above, and in further view of EP 2927636 A1 (hereinafter Tiequn). Regarding claim 17, Trichet teaches the system of claim 14, further comprising an actuator operably coupled to the optical microcavity (fig. elements 31, 30), the actuator configured to adjust a cavity length L of the optical microcavity (col 10 lines 43-48). The modified apparatus of Trichet does not teach an actuator operably coupled to the PDH servo loop. Tiequn, from the same field of endeavor as Trichet, teaches an actuator operably coupled to the PDH servo loop (p. 3 para 2). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the invention to apply the teaching of Tiequn to the modified apparatus of Trichet to have an actuator operably coupled to the PDH servo loop in order to stabilize the laser frequency to the resonance of a reference ring cavity (p. 3 para 2). Claim(s) 22 is/are rejected under 35 U.S.C. 103 as being unpatentable over Trichet and Li as applied to claim(s) 1 above, and further in view of US20150362425A1 (hereinafter Goldsmith). Regarding claim 22, the modified device of Trichet does not teach the method of claim 1, wherein the change in the detected output light is detected with a signal-to-noise ratio of at least 75 for a diffusing particle having a molecular weight of no more than 100 kDa. Goldsmith, from the same field of endeavor as Trichet, teaches the method of claim 1, wherein the change in the detected output light is detected with a signal-to-noise ratio of at least 75 for a diffusing particle having a molecular weight of no more than 100 kDa (para [0107] lines 2-7; weight of one nanotube is less than 100 kDa). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the invention to apply the teaching of Goldsmith to the modified device of Trichet to have the method of claim 1, wherein the change in the detected output light is detected with a signal-to-noise ratio of at least 75 for a diffusing particle having a molecular weight of no more than 100 kDa in order to have an apparatus for single particle spectroscopy (para [0022]). Conclusion Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a). A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action. Any inquiry concerning this communication or earlier communications from the examiner should be directed to ROBERTO FABIAN JR whose telephone number is (571)272-3632. The examiner can normally be reached M-F (8-12, 1-5). Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, KARA GEISEL can be reached at (571)272-2416. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /ROBERTO FABIAN JR/Examiner, Art Unit 2877 /Kara E. Geisel/Supervisory Patent Examiner, Art Unit 2877
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Prosecution Timeline

May 05, 2025
Application Filed
Jan 23, 2026
Response after Non-Final Action
Jan 27, 2026
Non-Final Rejection mailed — §103
May 13, 2026
Examiner Interview Summary
May 13, 2026
Response Filed
Jun 08, 2026
Final Rejection mailed — §103 (current)

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Prosecution Projections

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Expected OA Rounds
71%
Grant Probability
96%
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