Kuo-Wei Huang

Three dimensional microfluidics with embedded microball lenses for parallel and high throughput multicolor fluorescence detection

We report a 3D microfluidic device with 32 detection channels and 64 sheath flow channels and embedded microball lens array for high throughput multicolor fluorescence detection. A throughput of 358 400 cells/s has been accomplished. This device is realized by utilizing solid immersion micro ball lens arrays for high sensitivity and parallel fluorescence detection. High refractive index micro ball lenses (n = 2.1) are embedded underneath PDMS channels close to cell detection zones in channels. This design permits patterning high N.A. micro ball lenses in a compact fashion for parallel fluorescence detection on a small footprint device. This device also utilizes 3D microfluidic fabrication to address fluid routing issues in two-dimensional parallel sheath focusing and allows simultaneous pumping of 32 sample channels and 64 sheath flow channels with only two inlets.

Tunnel Dielectrophoresis for Tunable, Single‐Stream Cell Focusing in Physiological Buffers in High‐Speed Microfluidic Flows

A novel tunnel dielectrophoresis (TDEP) mechanism is demonstrated for continuously tunable, sheathless, 3D, and single-stream microparticle and cell focusing in high-speed flows in regular physiological buffers. Particles and cells showing negative DEP responses can be focused at the electric field minimum location regardless of their types and sizes.

Fabrication of 3D high aspect ratio PDMS microfluidic networks with a hybrid stamp

We report a novel methodology for fabricating large-area, multilayer, thin-film, high aspect ratio, 3D microfluidic structures with through-layer vias and open channels that can be bonded between hard substrates. It is realized by utilizing a hybrid stamp with a thin plastic sheet embedded underneath a PDMS surface. This hybrid stamp solves an important edge protrusion issue during PDMS molding while maintaining necessary stamp elasticity to ensure the removal of PDMS residues at through-layer regions. Removing edge protrusion is a significant progress toward fabricating 3D structures since high aspect ratio PDMS structures with flat interfaces can be realized to facilitate multilayer stacking and bonding to hard substrates. Our method also allows for the fabrication of 3D deformable channels, which can lead to profound applications in electrokinetics, optofluidics, inertial microfluidics, and other fields where the shape of the channel cross section plays a key role in device physics. To demonstrate, as an example, we have fabricated a microfluidic channel by sandwiching two 20 μm wide, 80 μm tall PDMS membranes between two featureless ITO glass substrates. By applying electrical bias to the two ITO substrates and pressure to deform the thin membrane sidewalls, strong electric field enhancement can be generated in the center of a channel to enable 3D sheathless dielectrophoretic focusing of biological objects including mammalian cells and bacteria at a flow speed up to 14 cm s(-1).

Optoelectronic tweezers integrated with 3D microfluidic networks

We report on a novel optoelectronic tweezers (OET) platform integrated with three-dimensional microfluidic networks to enable single-cell manipulation and advance fluid control functions such as mixing droplets and thermal cycles on a chip.

Fabricatiion of 3D microfluidic networks with a hybrid stamp

We report on a novel methodology for fabricating multilayer, high aspect ratio, 3D microfluidic structures with through-layer vias that can be bonded between two hard substrates. It is realized by using a plastic plate embedded PDMS stamp in soft lithography to obtain flat and open PDMS structures that can be stacked to form multiplayer 3D microfluidic networks in high yield without severe structure distortion. Our method also allows the control of the curvature of the channel sidewalls and the shape of channel cross section that may open up profound applications in electrokinetics, microoptics, and inertia microfluidics.

Microfluidic integrated optoelectronic tweezers

We report on a novel optoelectronic tweezers (OET) that integrates with multilayer PDMS based microfluidic devices for the first time. This is realized by coating the PDMS channels with a Au mesh electrode capable of providing an electrically conductive and optically transparent surface that bonds with an OET surface as well. Microfluidic integrated OET not only allows continuous delivery of biological samples such as media, cells, and particles into optical manipulation area but also on-chip microfluidic valves for fluid control.

A high throughput electrorotation flow cytometer for single-cell analysis in continuous flows

We report a novel microfluidic-based high-throughput electrorotation flow cytometer for label-free single-cell analysis in continuous flows. This is realized by a heterogeneously integrated microfluidic channel with electrodes for high precision 3D single stream focusing and electrorotation of cells in high speed flows. This device provides 4 orders of magnitude higher throughput than prior electrorotation based cytometers.

Optoelectronic tweezers integrating with lensless imaging for wide field interactive optical manipulation

We demonstrate an optoelectronic tweezer (OET) integrating with a lensless, ultra wide-field imaging system for real-time interactive optical manipulation over a large field of view. This system enables, for the first time, simultaneous on-chip detection and optical manipulation of individual 10-µm microparticles, size of average mammalian cells, over an area of 6.55× 4.92 mm2, a field of view 100 times larger than a typical 10x objective lens used in OET manipulation.