We present a droplet-based microfluidic system that enables CRISPR-based gene editing and high-th... more We present a droplet-based microfluidic system that enables CRISPR-based gene editing and high-throughput screening on a chip. The microfluidic device contains a 10 × 10 element array, and each element contains sets of electrodes for two electric field-actuated operations: electrowetting for merging droplets to mix reagents and electroporation for transformation. This device can perform up to 100 genetic modification reactions in parallel, providing a scalable platform for generating the large number of engineered strains required for the combinatorial optimization of genetic pathways and predictable bioengineering. We demonstrate the system’s capabilities through the CRISPR-based engineering of two test cases: (1) disruption of the function of the enzyme galactokinase (galK) in E. coli and (2) targeted engineering of the glutamine synthetase gene (glnA) and the blue-pigment synthetase gene (bpsA) to improve indigoidine production in E. coli.
Microdroplet-based technologies are ideally suited for a wide range of chemical and biological ap... more Microdroplet-based technologies are ideally suited for a wide range of chemical and biological applications. Although researchers have developed highly effective methods for handling droplets within microfluidic systems, difficulties remain for retrieving the inner contents of droplets (e.g., biomolecules, reagents, cells, and microbeads). To achieve this goal, here we demonstrate a versatile, continuous flow methodology for “lysing” microdroplets. Our microfluidic platform passively: (i) guides droplets between different liquids (i.e., oil flow and water flow), (ii) washes away the surfactant of microdroplets, and (iii) lyses the droplets to release their contents into the water flow. The presented system was employed to wash and lyse water-in-oil droplets (31.6 μm in diameter) as well as separate the contents from the oil within a few minutes.
Dynamic cell-based microarrays offer numerous benefits for biological applications such as cytoki... more Dynamic cell-based microarrays offer numerous benefits for biological applications such as cytokine detection, medical diagnostics, drug screening, and cellomics; however, current cell arraying techniques remain limited in terms of trapping density and device resettability. Here we demonstrate a resettable cell arraying system by utilizing simple geometric designs in microfluidic devices to manipulate microscale hydrodynamics. We show that arrays of individual bovine aortic endothelial cells (BAECs): (i) immobilize in designated trapping positions between microposts under forward fluidic flow, and (ii) release from the trapping sites under backward fluidic flow of 0.5X trypsin to reset the arrays.
Self-regulating fluidic components are critical to the advancement of micro/nanofluidic circuitry... more Self-regulating fluidic components are critical to the advancement of micro/nanofluidic circuitry for chemical and biological applications, including sample preparation on chip and point-of-care (POC) molecular diagnostics. Previously, a variety of diodic components have been developed to enable flow rectification in fluidic technologies (e.g., microscale drug delivery systems in which backflow could be medically harmful). In particular, prior works have utilized suspended microbeads as dynamic resistive elements to achieve microfluidic diodes for ultra-low Reynolds Number (i.e., Re < 0.25) applications; however, using spherical beads to block fluid flow through rectangular channels is inherently limited. To overcome this issue, here we present a microfluidic bead-based diode that uses a targeted circular-shaped microchannel for microbead docking to rectify fluid flow under Re ≤ 0.25 conditions. Experimental results revealed Diodicities (Di’s) ranging from 1.34±0.15 to 5.32±0.64 ...
Author(s): Iwai, Kosuke | Advisor(s): Lin, Liwei | Abstract: The combination of microfabrication ... more Author(s): Iwai, Kosuke | Advisor(s): Lin, Liwei | Abstract: The combination of microfabrication and microfluidics has enabled a variety of opportunities in making new tools for biological and diagnostic applications. For example, microdroplets-based systems have attracted lots of attentions in recent years due to potential advantages in controlled environments with fast reaction time, high-throughput and low noises. This work presents a number of advanced microfluidic systems in process, control and manipulation of microdroplets, including finger-powered pumps to generate microdroplets, continuous-flow rupture reactors for the rupture and content retrieval of microdroplets, and magnetic microcapsules for drug delivery applications. Prototype `finger-powered' pumping systems have been designed and constructed and integrated with passive fluidic diodes to pump microfluidics, including the formation of microdroplets. No electrical power is needed for pumping by using a human finge...
Here we present and demonstrate the concept of a versatile ‘human-powered’ cell encapsulation sys... more Here we present and demonstrate the concept of a versatile ‘human-powered’ cell encapsulation system for a wide variety of droplet-based point-of-care diagnostics applications. Several distinctive accomplishments have been achieved: (1) human finger as the actuation force for droplet generation, (2) integrated pump actuating both water and oil fluid at the same time, and (3) forming microdroplets containing cells with the T-junction microchannel. For the first time, we successfully demonstrated the formation of water droplets in oil by a human finger with average size of 120μm in diameter, and encapsulated cells in the microdroplets.
We report the development of novel core-shell particles that each carry an aqueous phase encapsul... more We report the development of novel core-shell particles that each carry an aqueous phase encapsulated by a magnetic shell, which enables remote targeting and on-demand delivery of therapeutic agents. Specifically, we present three distinct accomplishments: (1) the development of magnetic photopolymerizable poly(ethylene glycol) diacrylate (PEGDA)-based composite by incorporating up to 10%w/w of coated iron oxide nanoparticles (10 nm), which are uniformly dispersed in the polymer matrix, (2) the formation of magnetic capsules (123.5±5.4 μm in diameter with core diameters of 46.8±4 μm) via selective photopolymerization of the magnetic shells in a multi-stage microfluidic flowfocusing device, and (3) remote manipulation of the core-shell particles via an external magnetic field. These magnetic microcapsules would provide the ability to control the transport of encapsulated therapeutic agents to target sites (without degradation of compounds) as well as an on-demand rupturing strategy (...
Point-of-care (POC) and disposable biomedical applications demand low-power microfluidic systems ... more Point-of-care (POC) and disposable biomedical applications demand low-power microfluidic systems with pumping components that provide controlled pressure sources. Unfortunately, external pumps have hindered the implementation of such microfluidic systems due to limitations associated with portability and power requirements. Here, we propose and demonstrate a 'finger-powered' integrated pumping system as a modular element to provide pressure head for a variety of advanced microfluidic applications, including finger-powered on-chip microdroplet generation. By utilizing a human finger for the actuation force, electrical power sources that are typically needed to generate pressure head were obviated. Passive fluidic diodes were designed and implemented to enable distinct fluids from multiple inlet ports to be pumped using a single actuation source. Both multilayer soft lithography and injection molding processes were investigated for device fabrication and performance. Experimen...
We present a droplet-based microfluidic system that enables CRISPR-based gene editing and high-th... more We present a droplet-based microfluidic system that enables CRISPR-based gene editing and high-throughput screening on a chip. The microfluidic device contains a 10 × 10 element array, and each element contains sets of electrodes for two electric field-actuated operations: electrowetting for merging droplets to mix reagents and electroporation for transformation. This device can perform up to 100 genetic modification reactions in parallel, providing a scalable platform for generating the large number of engineered strains required for the combinatorial optimization of genetic pathways and predictable bioengineering. We demonstrate the system’s capabilities through the CRISPR-based engineering of two test cases: (1) disruption of the function of the enzyme galactokinase (galK) in E. coli and (2) targeted engineering of the glutamine synthetase gene (glnA) and the blue-pigment synthetase gene (bpsA) to improve indigoidine production in E. coli.
Microdroplet-based technologies are ideally suited for a wide range of chemical and biological ap... more Microdroplet-based technologies are ideally suited for a wide range of chemical and biological applications. Although researchers have developed highly effective methods for handling droplets within microfluidic systems, difficulties remain for retrieving the inner contents of droplets (e.g., biomolecules, reagents, cells, and microbeads). To achieve this goal, here we demonstrate a versatile, continuous flow methodology for “lysing” microdroplets. Our microfluidic platform passively: (i) guides droplets between different liquids (i.e., oil flow and water flow), (ii) washes away the surfactant of microdroplets, and (iii) lyses the droplets to release their contents into the water flow. The presented system was employed to wash and lyse water-in-oil droplets (31.6 μm in diameter) as well as separate the contents from the oil within a few minutes.
Dynamic cell-based microarrays offer numerous benefits for biological applications such as cytoki... more Dynamic cell-based microarrays offer numerous benefits for biological applications such as cytokine detection, medical diagnostics, drug screening, and cellomics; however, current cell arraying techniques remain limited in terms of trapping density and device resettability. Here we demonstrate a resettable cell arraying system by utilizing simple geometric designs in microfluidic devices to manipulate microscale hydrodynamics. We show that arrays of individual bovine aortic endothelial cells (BAECs): (i) immobilize in designated trapping positions between microposts under forward fluidic flow, and (ii) release from the trapping sites under backward fluidic flow of 0.5X trypsin to reset the arrays.
Self-regulating fluidic components are critical to the advancement of micro/nanofluidic circuitry... more Self-regulating fluidic components are critical to the advancement of micro/nanofluidic circuitry for chemical and biological applications, including sample preparation on chip and point-of-care (POC) molecular diagnostics. Previously, a variety of diodic components have been developed to enable flow rectification in fluidic technologies (e.g., microscale drug delivery systems in which backflow could be medically harmful). In particular, prior works have utilized suspended microbeads as dynamic resistive elements to achieve microfluidic diodes for ultra-low Reynolds Number (i.e., Re < 0.25) applications; however, using spherical beads to block fluid flow through rectangular channels is inherently limited. To overcome this issue, here we present a microfluidic bead-based diode that uses a targeted circular-shaped microchannel for microbead docking to rectify fluid flow under Re ≤ 0.25 conditions. Experimental results revealed Diodicities (Di’s) ranging from 1.34±0.15 to 5.32±0.64 ...
Author(s): Iwai, Kosuke | Advisor(s): Lin, Liwei | Abstract: The combination of microfabrication ... more Author(s): Iwai, Kosuke | Advisor(s): Lin, Liwei | Abstract: The combination of microfabrication and microfluidics has enabled a variety of opportunities in making new tools for biological and diagnostic applications. For example, microdroplets-based systems have attracted lots of attentions in recent years due to potential advantages in controlled environments with fast reaction time, high-throughput and low noises. This work presents a number of advanced microfluidic systems in process, control and manipulation of microdroplets, including finger-powered pumps to generate microdroplets, continuous-flow rupture reactors for the rupture and content retrieval of microdroplets, and magnetic microcapsules for drug delivery applications. Prototype `finger-powered' pumping systems have been designed and constructed and integrated with passive fluidic diodes to pump microfluidics, including the formation of microdroplets. No electrical power is needed for pumping by using a human finge...
Here we present and demonstrate the concept of a versatile ‘human-powered’ cell encapsulation sys... more Here we present and demonstrate the concept of a versatile ‘human-powered’ cell encapsulation system for a wide variety of droplet-based point-of-care diagnostics applications. Several distinctive accomplishments have been achieved: (1) human finger as the actuation force for droplet generation, (2) integrated pump actuating both water and oil fluid at the same time, and (3) forming microdroplets containing cells with the T-junction microchannel. For the first time, we successfully demonstrated the formation of water droplets in oil by a human finger with average size of 120μm in diameter, and encapsulated cells in the microdroplets.
We report the development of novel core-shell particles that each carry an aqueous phase encapsul... more We report the development of novel core-shell particles that each carry an aqueous phase encapsulated by a magnetic shell, which enables remote targeting and on-demand delivery of therapeutic agents. Specifically, we present three distinct accomplishments: (1) the development of magnetic photopolymerizable poly(ethylene glycol) diacrylate (PEGDA)-based composite by incorporating up to 10%w/w of coated iron oxide nanoparticles (10 nm), which are uniformly dispersed in the polymer matrix, (2) the formation of magnetic capsules (123.5±5.4 μm in diameter with core diameters of 46.8±4 μm) via selective photopolymerization of the magnetic shells in a multi-stage microfluidic flowfocusing device, and (3) remote manipulation of the core-shell particles via an external magnetic field. These magnetic microcapsules would provide the ability to control the transport of encapsulated therapeutic agents to target sites (without degradation of compounds) as well as an on-demand rupturing strategy (...
Point-of-care (POC) and disposable biomedical applications demand low-power microfluidic systems ... more Point-of-care (POC) and disposable biomedical applications demand low-power microfluidic systems with pumping components that provide controlled pressure sources. Unfortunately, external pumps have hindered the implementation of such microfluidic systems due to limitations associated with portability and power requirements. Here, we propose and demonstrate a 'finger-powered' integrated pumping system as a modular element to provide pressure head for a variety of advanced microfluidic applications, including finger-powered on-chip microdroplet generation. By utilizing a human finger for the actuation force, electrical power sources that are typically needed to generate pressure head were obviated. Passive fluidic diodes were designed and implemented to enable distinct fluids from multiple inlet ports to be pumped using a single actuation source. Both multilayer soft lithography and injection molding processes were investigated for device fabrication and performance. Experimen...
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Papers by Kosuke Iwai