# US 12,377,415 B2 · Photoactivated selective release (PHASR) of droplets from microwell arrays

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- Number: US 12,377,415 B2
- Document ID: US12377415B2
- Status: Granted
- Kind: B2
- Application number: 17/562,250
- Filed: 2021-12-27
- Published: 2022-06-30
- Granted: 2025-08-05
- Earliest claimed: 2020-12-30
- Assignees: The Trustees of the University of Pennsylvania
- Applicants: The Trustees of the University of Pennsylvania
- Inventors: Yongwon Choi; Daeyeon Lee; Junhyong Kim; Syung Hun Han
- Web page: https://patentgrep.com/patent/US12377415B2

## CPC

- B01L 3/502784: {specially adapted for droplet or plug flow, e.g. digital microfluidics}
- B01L 3/502715: {characterised by interfacing components, e.g. fluidic, electrical, optical or mechanical interfaces}
- B01L 3/50273: {characterised by the means or forces applied to move the fluids}
- B01L 3/502746: {characterised by the means for controlling flow resistance, e.g. flow controllers, baffles or throttle valves}
- B01L 3/50851: {specially adapted for heating or cooling samples}
- B81B 1/006: {Microdevices formed as a single homogeneous piece, i.e. wherein the mechanical function is obtained by the use of the device, e.g. cutters}
- G01N 15/1434: Optical arrangements
- G01N 15/1484: {microstructural devices}
- B01L 2200/027: for microfluidic devices
- B01L 2200/0689: Sealing
- B01L 2300/046: Function or devices integrated in the closure
- B01L 2300/0663: Whole sensors
- B01L 2300/0829: Multi-well plates; Microtitration plates
- B01L 2300/1872: Infrared light
- B01L 2400/0442: thermal energy, e.g. vaporisation, bubble jet
- B81B 2201/057: Micropipets, dropformers
- B81B 2203/033: Trenches
- B81B 2203/0338: Channels
- G01N 15/01: specially adapted for biological cells, e.g. blood cells (investigating sedimentation of particle suspensions in blood G01N15/05)
- B01L: CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
- B81B: MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES (piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/00, H10N35/00)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

Provided is photoactivated selective release (or PHASR) of droplets from a microwell array enabled by a photoresponsive polymer layer integrated into the microfluidic device. This photoresponsive layer is placed in between a microwell array that traps a large number of droplets and a monolithic flow chamber that can be used for recovery. By using focused light, the photoresponsive layer can either be punctured or induced to create local heating to selectively release droplets. The type of photoacoustic dye and the physical properties of the photoresponsive layer can be engineered to induce either puncture of the membrane or pushing of droplets out of the microwells with low thermal impact on the droplets. This approach has broad application in the field of soft lithography-based microfluidic devices for various applications including photoresponsive valves as well as high throughput single cell sequencing.

## Claims

### Claim 1

A microfluidic device comprising:
a well substrate having a plurality of wells defined in the well substrate, each well of the plurality of wells having a first opening and a second opening;
a photoresponsive layer sealing the first opening of each well of the plurality of wells; and
a trap channel in fluidic communication with the second opening of each well of the plurality of wells.

### Claim 2 (depends on 1)

The microfluidic device of claim 1 further comprising a collection device configured to guide a droplet from a well of the plurality of wells to a collection vessel.

### Claim 3 (depends on 2)

The microfluidic device of claim 2 wherein the collection device is configured to operate in an automated manner.

### Claim 4 (depends on 2)

The microfluidic device of claim 2 wherein the collection device comprises a pump, a valve, a conduit, or a combination thereof.

### Claim 5 (depends on 2)

The microfluidic device of claim 2 further comprising the collection vessel capable of fluidically communicating with the collection device.

### Claim 6 (depends on 2)

The microfluidic device of claim 2 wherein the collection device is configured to operate between a first state and a second state, wherein the first state defines a first flow path for the droplet and the second state define a second flow path for the droplet.

### Claim 7 (depends on 1)

The microfluidic device of claim 1 further comprising a first channel and wherein the photoresponsive layer prevents the first channel from fluidically communicating with the first opening of one or more wells of the plurality of wells.

### Claim 8 (depends on 7)

The microfluidic device of claim 7 further comprising a monolithic first channel substrate comprising the first channel formed in the monolithic first channel substrate.

### Claim 9 (depends on 1)

The microfluidic device of claim 1 wherein the well substrate is a monolithic well substrate.

### Claim 10 (depends on 1)

The microfluidic device of claim 1 wherein (a) the photoresponsive layer is essentially optically transparent, or (b) the photoresponsive layer exhibits a light absorption for light having a wavelength between about 750 nm and about 1400 nm, or (c) the photoresponsive layer has a glass transition temperature between about 35° C. and about 100° C., or a combination thereof.

### Claim 11 (depends on 1)

The microfluidic device of claim 1 wherein the photoresponsive layer comprises a dye or a plasticizer or both.

### Claim 12 (depends on 1)

The microfluidic device of claim 1 wherein (a) the plurality of wells is provided with a density of greater than 7,000 wells per cm2, or (b) the plurality of wells comprises at least 40,000 wells, or both (a) and (b).

### Claim 13 (depends on 1)

The microfluidic device of claim 1 wherein the plurality of well has a first well for containing a first content and a second well for containing a second content.

### Claim 14 (depends on 1)

The microfluidic device of claim 1 wherein one or more wells of the plurality of well has a (a) width between about 1 μm and about 1000 μm, or (b) a depth from between about 1 μm and about 1000 μm, or (c) a volume between about 0.5 pL and about 1.5 pL, or a combination of thereof.

### Claim 15 (depends on 1)

A system comprising:
the microfluidic device of claim 1;
an illumination train configured to illuminate a particular portion of the photoresponsive layer overlying a particular well of the plurality of wells, so as to:
(a) rupture the particular portion of the photoresponsive layer overlying the particular well, or
(b) expel contents in the particular well through the second opening of the particular well by forming a bubble within the particular well by heating the particular well or a region proximate to the particular well or both (a) and (b).

### Claim 16 (depends on 15)

The system of claim 15, wherein the illumination train is configured to illuminate individually each well of the plurality of wells.

### Claim 17 (depends on 15)

The system of claim 15, wherein the illumination train is configured to illuminate with light having a wavelength between about 750 nm and about 1400 nm the portion of the photoresponsive layer overlying the particular well.

### Claim 18 (depends on 15)

The system of claim 15 further comprising a monitoring train configured to (c) collect spectral data from one or more wells of the plurality of wells, or (d) collect one or more images of one or more wells of the plurality of well, or both (c) and (d).

### Claim 19 (depends on 18)

The system of claim 18, wherein the monitoring train is configured to illuminate individually each well of the plurality of wells.