# US 11,898,129 B2 · Microfluidic pressure regulator for robust hydrogel loading without bursting

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- Number: US 11,898,129 B2
- Document ID: US11898129B2
- Status: Granted
- Kind: B2
- Application number: 17/492,263
- Filed: 2021-10-01
- Published: 2022-01-27
- Granted: 2024-02-13
- Earliest claimed: 2015-10-23
- Assignees: The Regents of the University of California
- Applicants: The Regents of the University of California
- Inventors: Abraham P. Lee; Xiaolin Wang; Duc Phan; Christopher C. W. Hughes; Steven C. George
- Web page: https://patentgrep.com/patent/US11898129B2

## CPC

- C12M 23/16: {Microfluidic devices; Capillary tubes (integrated microfluidic structures B01L3/5027; microreactors B01J19/0093)}
- B01L 3/502738: {characterised by integrated valves (throttle valves in microfluidic sample containers B01L3/502746)}
- C12M 21/08: {for producing artificial tissue or for ex-vivo cultivation of tissue (prostheses A61F2/00, grafts A61L27/00)}
- C12M 29/10: {Perfusion}
- C12M 41/40: {of pressure}
- B01L 3/502761: {specially adapted for handling suspended solids or molecules independently from the bulk fluid flow, e.g. for trapping or sorting beads or physically stretching molecules}
- B01L 2200/0647: Handling flowable solids, e.g. microscopic beads, cells, particles
- B01L 2300/0864: comprising only one inlet and multiple receiving wells, e.g. for separation, splitting
- B01L 2400/0688: surface tension valves, capillary stop, capillary break
- C12M: APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; {APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS}
- B01L: CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE

## Abstract

A pressure regulator module for a chip-based microfluidic platform is provided. The module includes a microfluidic channel for passing flowable material from the inlet region through the outlet region and into a downstream compartment; one or more microvalves fluidly connected to the microfluidic channel and upstream of the outlet region; and one or more reservoirs fluidly connected to the microvalves, for receiving flowable material diverted by the microvalves, where a flow of flowable material passing from the inlet region toward the downstream compartment is at least partially diverted by the microvalves into the reservoirs as a result of a pressure increase in the microfluidic channel. In some versions, the microvalves are capillary burst valves. A microfluidic chip containing the module and a method of using the module are provided.

## Claims

### Claim 1

A method of loading a flowable material into a compartment of an on-chip microfluidic platform, comprising
passing a flowable material from an inlet region of a microfluidic channel to a downstream outlet region of the microfluidic channel and into a compartment fluidly connected to an outlet region, and
diverting, a part of the flowable material from the microfluidic channel through a bypass channel into a reservoir, the bypass channel being fluidity connected via a pressure safety capillary burst valve to the microfluidic channel upstream of the compartment, wherein the flowable material is diverted when the hydraulic pressure inside the microfluidic channel is higher than the pressure safety capillary burst valve burst pressure.

### Claim 2 (depends on 1)

The method of claim 1, wherein the compartment comprises one or more fluidly connected tissue chambers for culturing cells or microtissues.

### Claim 3 (depends on 1)

The method of claim 1, wherein the compartment comprises one or more fluidly connected tissue chambers for culturing cells or microtissues, and each tissue chamber comprises at least two capillary burst valves for perfusing nutrients through the tissue chamber, and wherein the capillary burst valves located upstream of the compartment have lower burst pressures than the capillary burst valves of the tissue chambers.

### Claim 4 (depends on 3)

The method of claim 3, wherein the tissue chambers contain flowable material that forms an air-flowable material interface at each capillary burst valve of the tissue chambers, and wherein the diverting of flowable material from the microfluidic channel maintains each interface.

### Claim 5 (depends on 1)

The method of claim 1, wherein the flowable material comprises a cell-hydrogel mixture.

### Claim 6 (depends on 1)

The method of claim 1, wherein the flowable material is manually or automatically passed from the inlet region to the downstream outlet region.