Prosecution Insights
Last updated: April 19, 2026
Application No. 16/287,023

Directing Motion of Droplets Using Differential Wetting

Non-Final OA §103
Filed
Feb 27, 2019
Examiner
KAUR, GURPREET
Art Unit
1759
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Volta Labs Inc.
OA Round
9 (Non-Final)
65%
Grant Probability
Moderate
9-10
OA Rounds
3y 7m
To Grant
99%
With Interview

Examiner Intelligence

Grants 65% of resolved cases
65%
Career Allow Rate
496 granted / 766 resolved
At TC average
Strong +37% interview lift
Without
With
+36.7%
Interview Lift
resolved cases with interview
Typical timeline
3y 7m
Avg Prosecution
28 currently pending
Career history
794
Total Applications
across all art units

Statute-Specific Performance

§101
0.7%
-39.3% vs TC avg
§103
49.8%
+9.8% vs TC avg
§102
21.0%
-19.0% vs TC avg
§112
21.1%
-18.9% vs TC avg
Black line = Tech Center average estimate • Based on career data from 766 resolved cases

Office Action

§103
DETAILED ACTION Status of the Claims 1. Claims 2-4, 6-7, 10, 13-18, 32, 33, 35-36 and 50-55 are pending. Claims 32, 33 and 35-36 are withdrawn. Continued Examination Under 37 CFR 1.114 2. A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 1/07/2026 has been entered. Status of the Rejections 3. Rejection of claims in view of Kaler et al. and Lee et al. and Abdelgawad et al. in view of Lee et al. are being withdrawn in view of applicant’s amendments. New grounds of rejection is as follow. Claim Rejections - 35 USC § 103 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. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or nonobviousness. 4. Claim(s) 2-4, 6-7, 10, 13-18 and 50-55 is/are rejected under 35 U.S.C. 103 as being unpatentable over Abdelgawad et al. (Microfluid Nanofluid, 2008, 4: 349-355) in view of Lee et al. (Langmuir, 2013, 7758-7767), Sista et al. (US 2015/0107995), Huguchi et al. (US 2018/0272335) and Kaler et al. (US 2015/0259754). Claim 2, Abdelgawad et al. teach an apparatus (digital microfluidic device) for controlling motion of liquid droplets (moving the droplet) (see section 3.2 and Fig 3) comprising: a set of electrode pads (electrode array) (see Fig 3) configured to: subject a liquid droplet comprising the first liquid to motion over a sequence of the set of electrodes (water droplet is moved over the array of electrodes; see section 3.2 and Fig 3), wherein the set of electrodes are provides on an open surface wherein the open surface has no overlying or facing electrode or plate (the apparatus is single-sided (see Fig 3a), thus it is open with no overlying or facing electrode or plate); a gap filling material disposed between two or more adjacent electrodes of the set of electrodes, wherein the gap filling material and the two or more adjacent electrodes comprise a planarized surface (saran wrap is deposited on the electrodes and disposed in-between the adjacent electrodes; see section 3.2 and Fig 3a and as seen from Fig 3a, the saran wrap and the electrodes comprise planarize surface); a dielectric disposed over the planarized surface, wherein the dielectric is different from the gap material (Rain-x hydrophobic coating is disposed over the electrodes which is different from saran wrap gap filling material; see section 3.2 and Fig 3); a liquid layer comprised of second liquid is disposed over dielectric layer and second liquid is immiscible/support with/the droplet, (peanut oil is disposed over hydrophobic coating of Rain-x which is immiscible with the water droplet; see section 3.2 and Fig 3); the liquid layer comprises a second liquid that has a wetting affinity for the dielectric (the electrodes are energized to move the droplet over the electrode see section 3.2 and Fig 3, thus second liquid has wetting affinity for dielectric) and; a controller operatively coupled to the set of electrodes, wherein the controller is configured to direct at least the sequence of the set of electrodes to generate an electric field to alter a wetting characteristic of at least portion of the dielectric, thereby inducing motion of the liquid droplet over the sequence of the set of electrodes (a controller is coupled to electrodes and is designed to energized the electrodes in desired sequence to move the droplet over the electrode path, thus changing the wetting characteristic of the dielectric layer; see sections 2.1 and 3.2 and Fig 3). Abdelgawad et al. teach a Rain-x hydrophobic coating is disposed over the electrodes but do not teach the dielectric layer is mechanically held and stretched over the planarized surface. However, Lee et al. teach electrowetting-on-dielectric (EWOD) device for moving the droplet comprised of either unstretched or stretched Teflon layer (reads on dielectric layer) disposed on electrodes. The stretched dielectric layer provides better wettability and less drop bouncing compared to upstretched dielectric layer (see section 4.1 and 4.2). Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention in view of Lee et al. teaching to stretch the hydrophobic coating of Abdelgawad et al. over the electrodes because it would provide better wettability and less drop bouncing. Combined teachings of Abdelgawad et al. and Lee et al. teach mineral oil is disposed over stretched dielectric layer which is immiscible with the droplet and liquid droplet rides on an upper surface formed by the oil and it is examiner’s position the combined teachings of Abdelgawad et al. and Lee et al. device which has same structural elements of oil being disposed over smoothed dielectric layer as that of claimed invention, thus would have same surface property to impart a slide angle for 5 ul droplet of no more than 10 degrees. Abdelgawad et al. do not teach a locatable carriage comprising dispenser, wherein the locatable carriage is configured to motion parallel to the liquid layer configured to support the liquid droplet and wherein the dispenser is configured to dispense the liquid droplet. However, Sista et al. teach droplets could be loaded onto the droplet actuator using pressure assisted loading or robotic loading or passive loading and pipette loading [0043][0042]. Furthermore, Huguchi et al. teach robotic loading comprised of liquid droplet ejecting unit 251 on a support mechanism which is capable of moving the droplet ejecting unit in both X or Y direction in reference to the well plate [0071]-[0076] thereby by dispensing accurate volume of the droplet. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention in view of Sista et al. and Huguchi et al. teaching to substitute manual pipette of Abdelgawad et al. with droplet ejecting device for dispensing accurate volume of the droplet onto the liquid layer. Abdelgawad et al. do not teach one or more heating elements configured to heat the liquid droplet on the open surface. However, Kaler et al. teach droplet-based microfluidic device comprised of plurality of micro-electrodes disposed on single unit substrate [0018][0019]0022] and heating elements configured provide necessary reaction temperatures [0011][0012][0023]. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention in view of Kaler et al. teaching to add heating elements in the Abdelgawad et al. device to provide necessary reaction temperatures. Claim 4, Abdelgawad et al. teach the liquid droplet rides on an upper surface formed by the oil (Figs 3b-d]). Claims 6 and 7 is/are considered product-by-process claims. The cited prior art teaches all of the positively recited structure of the claimed apparatus or product. The determination of patentability is based upon the apparatus structure itself. The patentability of a product or apparatus does not depend on its method of production or formation. If the product in the product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process. See In re Thorpe, 777 F.2d 695, 698, 227 USPQ 964, 966 (Fed. Cir. 1985) (see MPEP § 2113). Claim 10, Abdelgawad et al. teach the liquid layer is oil i.e. peanut oil (see section 3.3 which is inherently both dielectric and hydrophobic as evidenced by applicant (see PGPUB [0149]). Claims 13-14, Combined teachings of Abdelgawad et al. and Lee et al. teach peanut oil is disposed over stretched dielectric layer which is immiscible with the droplet and liquid droplet rides on an upper surface formed by the oil and it is examiner’s position the combined teachings of Abdelgawad et al. and Lee et al. device which has same structural elements of oil being disposed over smoothed dielectric layer as that of claimed invention, thus would have same surface property to impart a slide angle for 5 ul droplet of no more than 3 or 1 degree. Claim 53, modified Abdelgawad et al. teach the liquid droplet ejecting unit 251 on a support mechanism which is capable of moving the droplet ejecting unit in both X or Y direction in reference to the well plate (see Huguchi et al. [0071]-[0076]). Claim 55, Abdelgawad et al. teach the set of electrodes comprises a plurality of tracks for moving the liquid droplets on the open surface with no overlying or facing electrode or plate above the liquid droplets (plurality of track of electrodes for moving liquid droplets; see Figs 1a-d). Claim 15, Abdelgawad et al. teach method (see section 3.2 and Fig 3]) comprising steps of: (a) dispensing a liquid droplet comprising a first liquid onto liquid layer provided adjacent to an open surface, wherein the open surface has no overlying or facing electrode or plate, wherein the liquid layer comprises a second liquid, wherein the liquid layer is disposed over a set of electrode pads (dispensing water droplet onto open surface of substrate with no overlaying electrode/plate, the water droplet is placed onto peanut oil of second liquid, wherein the oil is placed over the plurality of electrodes; see section 3.2 and Fig 3); a gap filling material disposed between two or more adjacent electrodes of the set of electrodes, wherein the gap filling material and the two or more adjacent electrodes comprise a planarized surface (Saran wrap is deposited on the electrodes and disposed in-between the adjacent electrodes; see section 3.2 and Fig 3a, as seen from Fig 3a, the Saran wrap and the electrodes comprise planarize surface); a dielectric disposed over the planarized surface, wherein the dielectric is different from the gap filing material (Rain-x hydrophobic coating is disposed over the electrodes which is different from the saran wrap gap filling material; see section 3.2 and Fig 3); a liquid layer comprised of second liquid is disposed over dielectric layer and second liquid is immiscible/support with/the droplet, (peanut oil is disposed over hydrophobic coating of Rain-x which is immiscible with the water droplet; see section 3.2 and Fig 3); the second liquid that has a wetting affinity for the dielectric (the electrodes are energized to move the droplet over the electrode; see section 3.2 and Fig 3, thus second liquid has wetting affinity for dielectric) and the set of electrodes is configured to generate electric field; see section 3.2 and Fig 3; and b) causing at least the sequence of the set of electrodes to generate electric field to alter a wetting characteristic of a portion of the liquid layer, the dielectric, the planarized surface, or any combination thereof, thereby inducing motion of the droplet over the sequence of the set of electrodes (the electrodes are energized in desired sequence to move the droplet over the electrode path, thus changing the wetting characteristic of the dielectric layer; see sections 2.1 and 3.2 and Fig 3). Abdelgawad et al. teach a Rain-x hydrophobic coating is disposed over the electrodes but do not teach the dielectric layer is mechanically held and stretched over the planarized surface. However, Lee et al. teach electrowetting-on-dielectric (EWOD) device for moving the droplet comprised of either unstretched or stretched Teflon layer (reads on dielectric layer) disposed on electrodes. The stretched dielectric layer provides better wettability and less drop bouncing compared to upstretched dielectric layer (see section 4.1 and 4.2). Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention in view of Lee et al. teaching to stretch the hydrophobic coating of Abdelgawad et al. over the electrodes because it would provide better wettability and less drop bouncing. Combined teachings of Abdelgawad et al. and Lee et al. teach mineral oil is disposed over stretched dielectric layer which is immiscible with the droplet and liquid droplet rides on an upper surface formed by the oil and it is examiner’s position the combined teachings of Abdelgawad et al. and Lee et al. device which has same structural elements of oil being disposed over smoothed dielectric layer as that of claimed invention, thus would have same surface property to impart a slide angle for 5 ul droplet of no more than 10 degrees. Abdelgawad et al. do not teach a locatable carriage comprising dispenser, wherein the locatable carriage is configured to motion parallel to the liquid layer configured to support the liquid droplet and wherein the dispenser is configured to dispense the liquid droplet. However, Sista et al. teach droplets could be loaded onto the droplet actuator using pressure assisted loading or robotic loading or passive loading and pipette loading [0043][0042]. Furthermore, Huguchi et al. teach robotic loading comprised of liquid droplet ejecting unit 251 on a support mechanism which is capable of moving the droplet ejecting unit in both X or Y direction in reference to the well plate [0071]-[0076] thereby by dispensing accurate volume of the droplet. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention in view of Sista et al. and Huguchi et al. teaching to substitute manual pipette of Abdelgawad et al. with droplet ejecting device for dispensing accurate volume of the droplet onto the liquid layer. Abdelgawad et al. do not teach heating the liquid droplet when the liquid droplet mover over the set of electrodes. However, Kaler et al. teach droplet-based microfluidic device comprised of plurality of micro-electrodes disposed on single unit substrate [0018][0019]0022] and heating the droplet during actuation to provide necessary reaction temperatures [0011][0012][0023]. Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention in view of Kaler et al. teaching to heat the liquid droplet in the Abdelgawad et al. method to provide necessary reaction temperatures. Claim 17, Abdelgawad et al. teach the liquid droplet rides on an upper surface formed by the oil (Figs 3b-d]). Claim 18, Abdelgawad et al. teach the electrodes are printed on a PCB substrate (see col. ). Claims 50 and 51, modified Abdelgawad et al. teach the droplet loading could be done either via vibrating membrane pump or acoustic force (see Sista et al; [0042]) Claim 52, modified Abdelgawad et al. teach the liquid droplet ejecting unit 251 on a support mechanism which is capable of moving the droplet ejecting unit in both X or Y direction in reference to the well plate (see Huguchi et al. [0071]-[0076]). Claim 54, Abdelgawad et al. teach the set of electrodes comprises a plurality of tracks for moving the liquid droplets on the open surface with no overlying or facing electrode or plate above the liquid droplets (plurality of track of electrodes for moving liquid droplets; see Figs 1a-d). Response to Arguments Applicant’s arguments with respect to claim(s) 2 and 15 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. Applicant argues on page 10 of remarks that cited reference Abdelgawad teach two-plate actuation in which droplets are sandwiched between plates to reduce evaporation and furthermore incorporating heating element to heat liquid droplet on an open surface would frustrate the intended purpose of manipulating the liquid droplet. In response, examiner respectfully disagrees with applicant’s assertion. At first, Abdelgawad teaches two types of system including single plate actuation, which includes droplet dispensed on single plate with open surface (see section 3.2) and a two-plate actuation, which includes droplet sandwiched between two plates (see section 3.3). Additionally, incorporating heating element to Abelgawad single plate actuation system as taught by Kaler would not diminish the intended purpose of actuating the liquid droplet, as Kaler teaches heat is applied for necessary reaction temperatures to actuate the liquid droplet [0011][0016] and thus application of heat is not intended to evaporate or stop actuating the liquid droplet as asserted by applicant. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to GURPREET KAUR whose telephone number is (571)270-7895. The examiner can normally be reached M-F 9:30-6. 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, Curtis Mayes can be reached at 571-272-1234. 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. /GURPREET KAUR/ Primary Examiner Art Unit 1759
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Prosecution Timeline

Feb 27, 2019
Application Filed
Mar 23, 2021
Non-Final Rejection — §103
Jul 08, 2021
Interview Requested
Jul 23, 2021
Examiner Interview Summary
Aug 26, 2021
Response Filed
Nov 19, 2021
Final Rejection — §103
Feb 14, 2022
Interview Requested
Feb 26, 2022
Examiner Interview Summary
Apr 22, 2022
Response after Non-Final Action
May 02, 2022
Examiner Interview (Telephonic)
May 04, 2022
Request for Continued Examination
May 04, 2022
Response after Non-Final Action
May 05, 2022
Response after Non-Final Action
May 19, 2022
Interview Requested
May 27, 2022
Examiner Interview Summary
Jun 04, 2022
Non-Final Rejection — §103
Sep 15, 2022
Interview Requested
Sep 21, 2022
Examiner Interview Summary
Dec 09, 2022
Response Filed
Feb 01, 2023
Final Rejection — §103
Jun 01, 2023
Applicant Interview (Telephonic)
Jun 02, 2023
Examiner Interview Summary
Jun 08, 2023
Response after Non-Final Action
Aug 03, 2023
Request for Continued Examination
Aug 05, 2023
Response after Non-Final Action
Aug 15, 2023
Non-Final Rejection — §103
Oct 25, 2023
Applicant Interview (Telephonic)
Oct 31, 2023
Examiner Interview Summary
Nov 20, 2023
Response Filed
Dec 15, 2023
Examiner Interview (Telephonic)
Jul 29, 2024
Final Rejection — §103
Oct 29, 2024
Request for Continued Examination
Oct 30, 2024
Response after Non-Final Action
Nov 19, 2024
Non-Final Rejection — §103
May 21, 2025
Response Filed
Jul 07, 2025
Final Rejection — §103
Jan 07, 2026
Request for Continued Examination
Jan 11, 2026
Response after Non-Final Action
Jan 21, 2026
Non-Final Rejection — §103 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

9-10
Expected OA Rounds
65%
Grant Probability
99%
With Interview (+36.7%)
3y 7m
Median Time to Grant
High
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