Hou-Pu Chou

A Microfabricated Rotary Pump

Because microfluidic devices operate at low Reynolds number, many fluidic operations are limited by diffusion. We have developed a microfabricated rotary pump and demonstrated that active mixing can be used to overcome the slow diffusion process in two applications. First, we showed that mixing of reagents could be efficiently accomplished for objects of a wide range of diffusion constants. Second, we showed how reaction kinetics of a surface-binding assay can be enhanced by nearly two orders of magnitude.

Design, Fabrication, and Characterization of Form-Birefringent Multilayer Polarizing Beam Splitter

Polarizing beam splitters that use the anisotropic spectral reflectivity (ASR) characteristic of high-spatial-frequency multilayer binary gratings have been designed, fabricated, and characterized. Using the ASR effect with rigorous coupled-wave analysis, we design an optical element that is transparent for TM polarization and reflective for TE polarization at an arbitrary incidence angle and operational wavelength. The experiments with the fabricated element demonstrate a high efficiency (97), with polarization extinction ratios higher than 220:1 at a wavelength of 1.523 m over a 20 angular bandwidth by means of the ASR characteristics of the device. These ASR devices combine many useful characteristics, such as compactness, low insertion loss, high efficiency, and broad angular and spectral bandwidth operations.

Microfabricated devices for sizing DNA and sorting cells

We have microfabricated devices to size and sort microscopic biological objects, ranging from cells to single molecules of DNA. Sizing is accomplished by fluorescent excitation and detection. The devices are fabricated in a silicone elastomer using a replica method. Single molecules of DNA have been sized to 10 percent accuracy, and manipulation of E. Coli cells has been demonstrated.