Prosecution Insights
Last updated: April 19, 2026
Application No. 18/336,071

MICROFLUID COOLING FOR NON-UNIFORM HEATMAP

Final Rejection §103
Filed
Jun 16, 2023
Examiner
CAO, CHUN
Art Unit
2115
Tech Center
2100 — Computer Architecture & Software
Assignee
International Business Machines Corporation
OA Round
2 (Final)
85%
Grant Probability
Favorable
3-4
OA Rounds
2y 9m
To Grant
97%
With Interview

Examiner Intelligence

Grants 85% — above average
85%
Career Allow Rate
866 granted / 1021 resolved
+29.8% vs TC avg
Moderate +12% lift
Without
With
+12.2%
Interview Lift
resolved cases with interview
Typical timeline
2y 9m
Avg Prosecution
26 currently pending
Career history
1047
Total Applications
across all art units

Statute-Specific Performance

§101
11.5%
-28.5% vs TC avg
§103
25.9%
-14.1% vs TC avg
§102
33.1%
-6.9% vs TC avg
§112
16.3%
-23.7% vs TC avg
Black line = Tech Center average estimate • Based on career data from 1021 resolved cases

Office Action

§103
FINAL REJECTION The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Claims 1-25 are presented for examination. Claims 24-25 are withdrawn from consideration. 2. The text of those applicable section of Title 35, U.S. Code not included in this action can be found in the prior Office Action. 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. 3. 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. 4. Claims 1-23 are rejected under 35 U.S.C. 103 as being unpatentable over Paik et al (Paik), IEEE “Adaptive Cooling of Integrated Circuits Using Digital Microfluidics”1 in view of Liu et al. (Liu), US publication no. 2004/0112568 A1. As per claim 1, Paik teaches a method of microfluid cooling for a non-uniform Heatmap [section III "Adaptive hot-spot cooling concept and design", pages 434-437, figures 1-7], the method comprising: identifying a plurality of zones of a microelectronic device; obtaining a local temperature measurement for one or more zones of the plurality of zones of the microelectronic device [sub section “A Requirements for Adaptive Hot-Spot Cooling”, page 434; “Feedback Control Mechanisms”, page 437]; and applying a voltage to a microfluid in at least a portion of the one or more zones based on the obtained local temperature measurement [sub-section "Electrowetting based actuation of droplets", “Droplet Transport”, pages 435-436]. Paik does not explicitly disclose a microelectronic device comprising a coolant channel; while a microfluid is flowing through the coolant channel; applying a voltage to a segment of the coolant channel; wherein the applying increases a flow rate of the microfluid while the microfluid is flowing through the segment. Liu discloses a microelectronic device comprising a coolant channel [15, figure 1]; while a microfluid is flowing through the coolant channel; applying a voltage to a segment of the coolant channel [para 21; wherein the applying increases a flow rate of the microfluid while the microfluid is flowing through the segment [para 21, 23]. It would have been obvious to one of ordinary skill in the art at time the invention to combine the teachings of Paik and Liu because they both disclose a heat transfer device, the specify teachings of Liu stated above would have further enhanced the performance and functionality of Paik system to obtain predictable results to control a flow rate of fluid. Paik teaches: Page 434 3) System should be able to detect the changing thermal profile of the IC. To appropriately respond to increased heat densities or hot spots on an IC, the system requires a method to monitor these changes. Several methods to detect these changing thermal profiles are discussed toward the end of this section. 4) System should be able to adapt itself in response to a changing thermal profile. Once a change in the thermal profile has been detected, a response to the cooling device should be invoked in order to address this change. This requires the system to have a cooling mechanism that is reconfigurable such that improved cooling rates are applied where they are needed (e.g., hot spots on the chip). Page 435 Electrowetting-Based Actuation of Droplets: In electrowetting-based actuation of droplets, electrical fields are used to induce surface tension gradients. This method takes advantage of the electrowetting effect, in which the surface energy can be directly modified by the application of an electric field. The electric field results in a decrease in the contact angle, causing the droplet to spread or effectively wet the surface. If we divide the bottom electrode into discrete electrodes, as shown in Fig. 2, we can induce motion in the droplet to any adjacent electrode simply by applying voltages to that electrode. A custom electronic controller was made to independently address and provide high voltages to each electrode. A custom-written program was used to easily toggle each electrode in an automated and programmatic manner. This fundamental method of actuation is the basis on which the three basic microfluidic operations for adaptive cooling are built. Page 437 Feedback Control Mechanisms: Feedback of an IC' s thermal profile is crucial to the success of any adaptive cooling platform, as it provides a mechanism for which on-the-fly reconfigurability of droplet flow can work. There are two primary mechanisms for droplet flow control, each offering their own tradeoffs in terms of flexibility, sensing, and computational overhead. The first is thermal sensor feedback, where an array of temperature sensors maps the thermal profile of an IC for feedback to the droplet actuation system. Droplet generation rates, flow paths, and flow rates can be dynamically adjusted based on the thermal profile on the chip. This completely regulated approach offers the maximum flexibility as it dynamically adjust flow rates based on sensor readings, but it requires overhead for sensing, computation, and electronic control. Liu teaches: [0023] When a heat generator (such as a central processing unit of computer) produces heat taken away by a cooling fluid 5, the heated cooling fluid 5 flows through the conductive surface 10a, 10b into the plurality of micro channels 15a, 15b. According to size of the micro channels 15a, 15b, location of the heat exchanger 1, type of the fluid 5, velocity and temperature, the micro channels 15a, 15b have different mass flow rates of fluids as shown in FIGS. 7A, 7B and 7C, and the sensor unit 17 installed in each of the micro channels 15a, 15b measures and converts a mass flow rate of fluid depending on fluid physical properties (such as fluid flow, temperature, pressure, etc.) to an electric signal, whereby an external power source provides positive voltage to the electrode 16 corresponding to the electric signal in a manner that, an electrode in a micro channel having a relatively larger mass flow rate of fluid produces greater turbulence, and an electrode in a micro channel having a relatively smaller mass flow rate of fluid produces less turbulence, so as to minimize a boundary layer of a heat-transmission surface by turbulence and to increase fluid mixing and improve heat transfer performance. Furthermore, with greater turbulence being produced in a micro channel having a relatively larger mass flow rate of fluid, air bubbles or voids are easily formed in the flow field and may lead to increase in resistance of the flow field in the micro channel, making the external fluid 5 not easily enter into the micro channel, which thereby facilitates uniform fluid flows in different micro channels. In exemplification of a conventional diagram of mass flow rates shown in FIG. 7A, turbulence produced from the electrodes 16 increases resistance of central channels 35a, making relatively more fluids enter into side channels 35b in which mass flow rates of fluids are enhanced for facilitating uniform fluid flows in different channels as shown in FIG. 3. Similarly, for example of conventional diagrams of mass flow rates shown in FIGS. 7B and 7C, turbulence from electrodes can also facilitate uniform fluid flows in different channels as shown in FIG. 3, thereby effectively improving heat dissipating efficiency and heat transfer performance of the micro heat exchanger. As per claim 2, Paik teaches the applying of the voltage alters intermolecular cohesion in the microfluid sub-section "Electrowetting based actuation of droplets", “Droplet Transport”, pages 435-436]. As per claim 3, Paik teaches the applying of the voltage induces a super diffusivity of the microfluid [sub-section "Electrowetting based actuation of droplets", “Droplet Transport”, pages 435-436;]. As per claim 4, Paik teaches the applying of the voltage alters an intermolecular dimensionality of the microfluid [sub-section "Electrowetting based actuation of droplets", “Droplet Transport”, pages 435-436; “IC Level Integration”, page 437]. As per claim 5, Paik teaches the micro fluid is water, wherein the applying of the voltage disrupts intermolecular hydrogen bonding in the water, and wherein a dimensionality prevalence of the water differs between the one or more zones and at least one other zone [sub-section "Electrowetting based actuation of droplets", “Droplet Transport”, pages 435-436; “IC Level Integration”, page 437]. As per claim 6, Paik teaches the one or more zones include a plurality of electrodes for the applying of the voltage [sub-section "Electrowetting based actuation of droplets", “Droplet Transport”, pages 435-436; “IC Level Integration”, page 437]. As per claim 7, Paik teaches the one or more zones include a plurality of electrodes oppositely disposed in pairs across a coolant channel for the applying of the voltage [sub-section "Electrowetting based actuation of droplets", “Droplet Transport”, pages 435-436; “Droplet Formation/Dispensing”, page 436; figure 4]. As per claim 8, Paik teaches of generating the non-uniform heatmap from the local obtained temperature measurement for the plurality of zones, and wherein the applying of the voltage is different for at least two zones of the plurality of zones based on the non-uniform heatmap [sub-section “A Requirements for Adaptive Hot-Spot Cooling”, page 434; "Electrowetting based actuation of droplets", “Droplet Transport”, pages 435-436; “Feedback Control Mechanisms”, Page 437]. As to claims 9-15, directed to a computer-readable storage medium storing the instructions to perform the method of steps executed by the system as set forth in claims 1-7. Therefore, it is rejected on the same basis as set forth hereinabove. As to claims 16-21 are contained the same limitations as claims 9-15. Therefore, same rejection is applied. As per claim 22, Paik teaches a method of microfluid cooling for a non-uniform heatmap, the method comprising: disposing electrodes on protruding contacts of a microelectronic device at least partially defining a coolant channel for a microfluid [subsection “C Design and Fabrication of Flow-Through Prototypes”, Page 438]; obtaining a plurality of local temperature measurements from temperature sensors disposed in different zones of the microelectronic device adjacent to corresponding segments of the coolant channel for the micro fluid; and applying a voltage to the micro fluid in the coolant channel using the disposed electrodes based on the obtained local temperature measurement [sub-section “A Requirements for Adaptive Hot-Spot Cooling”, page 434; "Electrowetting based actuation of droplets", “Droplet Transport”, pages 435-436; "Electrowetting based actuation of droplets", “Droplet Transport”, pages 435-436]. Paik does not explicitly disclose a microelectronic device comprising a coolant channel; while a microfluid is flowing through the coolant channel; applying a voltage to a segment of the coolant channel; wherein the applying increases a flow rate of the microfluid while the microfluid is flowing through the segment. Liu discloses a microelectronic device comprising a coolant channel [15, figure 1]; while a microfluid is flowing through the coolant channel; applying a voltage to a segment of the coolant channel [para 21; wherein the applying increases a flow rate of the microfluid while the microfluid is flowing through the segment [para 21, 23]. It would have been obvious to one of ordinary skill in the art at time the invention to combine the teachings of Paik and Liu because they both disclose a heat transfer device, the specify teachings of Liu stated above would have further enhanced the performance and functionality of Paik system to obtain predictable results to control a flow rate of fluid. As per claim 23, Paik teaches the protruding contacts of the microelectronic device are heat sources [subsection “C Design and Fabrication of Flow-Through Prototypes”, Page 438]. 5. Examiner's note: Examiner has cited particular paragraphs and columns and line numbers in the references as applied to the claims above for the convenience of the applicant. Although the specified citations are representative of the teachings of the art and are applied to the specific limitations within the individual claim, other passages and figures may apply as well. It is respectfully requested from the applicant in preparing responses, to fully consider the references in entirety as potentially teaching all or part of the claimed invention, as well as the context of the passage as taught by the prior art or disclosed by the examiner. MPEP 2141.02 VI: “PRIOR ART MUST BE CONSIDERED IN ITS ENTIRETY, INCLUDING DISCLOSURES THAT TEACH AWAY FROM THE CLAIMS." Response to Arguments 6. Applicant's arguments filed 3/5/26 have been fully considered but they are not persuasive. 7. Applicant’s arguments with respect to claim(s) 1-23 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. See detailed rejection indicated above. Conclusion 8. 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 extension fee 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 date of this final action. Any inquiry concerning this communication or earlier communications from the examiner should be directed to CHUN CAO whose telephone number is (571)272-3664. The examiner can normally be reached on M-F 7:30 am-4:00 pm. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Kamini Shah can be reached on 571-272-2279. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of an application may be obtained from the Patent Application Information Retrieval (PAIR) system. Status information for published applications may be obtained from either Private PAIR or Public PAIR. Status information for unpublished applications is available through Private PAIR only. For more information about the PAIR system, see http://pair-direct.uspto.gov. Should you have questions on access to the Private PAIR system, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). /CHUN CAO/Primary Examiner, Art Unit 2115 1 Paik is cited by applicant.
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Prosecution Timeline

Jun 16, 2023
Application Filed
Dec 11, 2025
Non-Final Rejection — §103
Feb 23, 2026
Interview Requested
Mar 03, 2026
Examiner Interview Summary
Mar 03, 2026
Applicant Interview (Telephonic)
Mar 05, 2026
Response Filed
Mar 19, 2026
Final Rejection — §103 (current)

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Prosecution Projections

3-4
Expected OA Rounds
85%
Grant Probability
97%
With Interview (+12.2%)
2y 9m
Median Time to Grant
Moderate
PTA Risk
Based on 1021 resolved cases by this examiner. Grant probability derived from career allow rate.

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