Jessica Godin

Human mammalian cell sorting using a highly integrated micro-fabricated fluorescence-activated cell sorter (μFACS)

We demonstrate a high performance microfabricated FACS system with highly integrated microfluidics, optics, acoustics, and electronics. Single cell manipulation at a high speed is made possible by the fast response time (approximately 0.1 ms) of the integrated PZT actuator and the nozzle structure at the sorting junction. A Teflon AF-coated optofluidic waveguide along the microfluidic channel guides the illumination light, enabling multi-spot detection, while a novel space-time coding technology enhances the detection sensitivity of the microFACS system. The real-time control loop system is implemented using a field-programmable-gate-array (FPGA) for automated and accurate sorting. The microFACS achieves a high purification enrichment factor: up to approximately 230 fold for both polystyrene microbeads and suspended human mammalian cells (K562) at a high throughput (>1000 cells s(-1)). The sorting mechanism is independent of cell properties such as size, density, and shape, thus the presented system can be applied to sort out any pure sub-populations. This new lab-on-a-chip FACS system, therefore, holds promise to revolutionize microfluidic cytometers to meet cost, size, and performance goals.

Review Article: Recent advancements in optofluidic flow cytometer

There is an increasing need to develop optofluidic flow cytometers. Optofluidics, where optics and microfluidics work together to create novel functionalities on a small chip, holds great promise for lab-on-a-chip flow cytometry. The development of a low-cost, compact, handheld flow cytometer and microfluorescence-activated cell sorter system could have a significant impact on the field of point-of-care diagnostics, improving health care in, for example, underserved areas of Africa and Asia, that struggle with epidemics such as HIV∕AIDS. In this paper, we review recent advancements in microfluidics, on-chip optics, novel detection architectures, and integrated sorting mechanisms.

Demonstration of two-dimensional fluidic lens for integration into microfluidic flow cytometers

The focusing capabilities of a two-dimensional fluid-filled lens microfabricated in an optical polymer are demonstrated. The illumination path is visualized by localized scattering centers. Functionality for flow cytometry applications is demonstrated by localization of the excitation of large-angle scatter. Integrated in-plane optical systems offer simple, compact, and inexpensive alternatives to external optics, as well as the potential for increased detection efficiency and low-power operation.

Optofluidic Waveguides in Teflon AF-Coated PDMS Microfluidic Channels

We report a new method for fabricating an optofluidic waveguide that is compatible with polydimethylsiloxane (PDMS). The light path follows the microfluidic channels, an architecture that can maximize detection efficiency and make the most economic use of chip area in many lab-on-chip applications. The PDMS-based microfluidic channels are coated with Teflon amorphous fluoropolymers (Teflon AF) which has a lower refractive index (n = 1.31) than water (n = 1.33) to form a water/Teflon AF optical waveguide. Driven by a vacuum pump, the Teflon AF solution was flowed through the channels, leaving a thin (5-15 mum) layer of coating on the channel wall as the cladding layer of optical waveguides. This coating process resolves the limitations of spin-coating processes by reducing the elasticity mismatch between the Teflon AF cladding layer and the PDMS device body. We demonstrate that the resulting optofluidic waveguide confines and guides the laser light through the liquid core channel. Furthermore, the light in such a waveguide can be split when the fluid flow is split. This new method enables highly integrated biosensors such as lab-on-chip flow cytometers and micro-fabricated fluorescence-activated cell sorter with on-chip excitation.

Two-parameter angular light scatter collection for microfluidic flow cytometry by unique waveguide structures

Waveguide numerical aperture restrictions and light-blocking elements are used to create a microfluidic cytometer with both illumination and two-parameter light scatter collection systems integrated on-chip. Good forward scatter coefficients of variation (9.7-18.3%) are achieved for polystyrene beads under a reasonably high flow rate (28 cm/s) using a greatly simplified optical system.

Microfluidic Photonic Integrated Circuits.

We report on the development of an inexpensive, portable lab-on-a-chip flow cytometer system in which microfluidics, photonics, and acoustics are integrated together to work synergistically. The system relies on fluid-filled twodimensional on-chip photonic components such as lenses, apertures, and slab waveguides to allow for illumination laser beam shaping, light scattering and fluorescence signal detection. Both scattered and fluorescent lights are detected by photodetectors after being collected and guided by the on-chip optics components (e.g. lenses and waveguides). The detected light signal is imported and amplified in real time and triggers the piezoelectric actuator so that the targeted samples are directed into desired reservoir for subsequent advanced analysis. The real-time, closed-loop control system is developed with field-programmable-gate-array (FPGA) implementation. The system enables high-throughput (1- 10kHz operation), high reliability and low-powered (<1mW) fluorescence activated cell sorting (FACS) on a chip. The microfabricated flow cytometer can potentially be used as a portable, inexpensive point-of-care device in resource poor environments.

Integrated Fluidic Photonics for Multi-Parameter In-Plane Detection in Microfluidic Flow Cytometry

Cylindrical fluid-filled lenses microfabricated in polydimethylsiloxane (PDMS) polymer are incorporated into a microfluidic flow cytometer to localize excitation in the channel and enable multi-parameter in-plane scatter detection

Microfluidic Flow Cytometer with On-Chip Lens Systems for Improved Signal Resolution

We demonstrate a microfluidic flow cytometer lab-on-a-chip device employing fluid-filled lenses and a violet laser diode for light scattering measurements.

Two-dimensional lenses microfabricated in PDMS for integrated fluidic photonic devices

Focusing is demonstrated in fluid-filled microfabricated 2D lenses formed by an optical polymer. Such lenses can be integrated into fluidic photonic devices performing flow cytometry for increased detection efficiency and device functionality.

Forward and 90-degree light scattering measurements in optofluidic flow cytometer

A microfluidic flow cytometer for three-parameter light scatter measurements is demonstrated to distinguish between 4 sizes of polystyrene beads from 5-15 ∝ m. Light blocking and guiding elements are employed in this compact, integrated microfluidic chip.