Photoactivated selective release (PHASR) of droplets from microwell arrays
Inventors
Choi, Yongwon • Lee, Daeyeon • Kim, Junhyong • Han, Syung Hun
Assignees
University of Pennsylvania Penn
Publication Number
US-12377415-B2
Publication Date
2025-08-05
Expiration Date
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
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.
Core Innovation
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.
For a number of applications that involve trapping droplets in microarrays for extended periods, it is highly beneficial and desirable to recover droplets following the observation. Existing methods for selective recovery of droplets rely on mechanical actuation using pneumatic valves and/or optical tweezers, which methods require complicated control systems and also exhibit slow processing; applicability of this approach is limited by the fact that the number of valves must at least match the number of observation chambers, and capacity for capture and selective release based on this approach has been limited to a few hundreds, creating a long-felt need in the field for improved microfluidic devices configured to manipulate droplet samples.
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. The glass transition temperature and absorption spectra of the photoresponsive layer can be engineered, and incorporation of the photoresponsive layer minimally alters the chip fabrication process; selective recovery of the samples can be performed without relying on a large number of supporting instruments.
Claims Coverage
Overview: Two independent claims were identified, each defining a distinct inventive feature of the PHASR technology.
Well substrate sealed by a photoresponsive layer
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.
Illumination train for rupture or bubble-mediated expulsion
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).
The independent claims cover (1) a microfluidic device architecture comprising wells with first and second openings, a photoresponsive layer sealing the first openings, and a trap channel in fluidic communication with the second openings, and (2) a system adding an illumination train configured to induce membrane rupture or bubble-mediated expulsion at targeted wells.
Stated Advantages
Enables selective recovery of samples from microwell arrays without relying on a large number of supporting instruments.
Incorporation of the photoresponsive layer minimally alters the chip fabrication process.
Supports high-throughput operation and large array capacity; an illustrative experiment demonstrated PHASR from arrays consisting of 4,400 wells and arrays of 42,000 wells have been constructed.
Use of near-IR (NIR) illumination is described as far less harmful to biological molecules and cells than UV laser illumination.
Properties of the photoresponsive layer (e.g., glass transition temperature, absorption spectra, dye, plasticizer, thickness) can be tailored to meet specific sample requirements, enabling site-specific heating and controlled release.
Documented Applications
Photoresponsive valves.
High throughput single cell sequencing.
High-throughput assays that require extended incubation of droplets and recovery of analytes from a subset of captured droplets.
Phenotyping in combination with genotyping, such as applications in molecular biology and immunology.
Site-specific heating in various micro total analysis systems.
Culturing of cells or monitoring dynamic events within droplets for extended periods (hours to days), including applications such as single cell gene regulation, nuclear division and metabolism study.
Interested in licensing this patent?