Huangpin Ben Hsieh

Ultra-High-Throughput Microarray Generation and Liquid Dispensing Using Multiple Disposable Piezoelectric Ejectors

The authors have constructed an array of 12 piezoelectric ejectors for printing biological materials. A single-ejector footprint is 8 mm in diameter, standing 4 mm high with 2 reservoirs totaling 76 µL. These ejectors have been tested by dispensing various fluids in several environmental conditions. Reliable drop ejection can be expected in both humidity-controlled and ambient environments over extended periods of time and in hot and cold room temperatures. In a prototype system, 12 ejectors are arranged in a rack, together with an X - Y stage, to allow printing any pattern desired. Printed arrays of features are created with a biological solution containing bovine serum albumin conjugated oligonucleotides, dye, and salty buffer. This ejector system is designed for the ultra-high-throughput generation of arrays on a variety of surfaces. These single or racked ejectors could be used as long-term storage vessels for materials such as small molecules, nucleic acids, proteins, or cell libraries, which would allow for efficient preprogrammed selection of individual clones and greatly reduce the chance of cross-contamination and loss due to transfer. A new generation of design ideas includes plastic injection molded ejectors that are inexpensive and disposable and handheld personal pipettes for liquid transfer in the nanoliter regime. (Journal of Biomolecular Screening 2004:85-94)

Traveling wave bio-agent concentrator

This paper describes a hybrid bio-agent concentrator device based on the combined performance of a modified field flow fractionation system for particulate deposition and a traveling wave transport mechanism to deliver and concentrate particulates into a sample well. The device has been successfully tested on B. thurengiensis and polystyrene beads in the threat range of 1-10 /spl mu/m. This MEMS device may increase the concentration of post-ultrafiltration retentates or post-aerosol collected hydrosols by another 100X. As a front-end to detection, it will enhance the effective sensitivity of the detector. The device may also have bio medical implications in bio separation and cell enrichment.

Particle simulation of traveling wave gel electrophoresis

This paper describes a 3D particle model to simulate conventional DC and traveling wave gel electrophoresis. Traveling waves sustain much higher fields for increased speed, but require much lower voltage which does not scale with gel dimension. Secondary refinement after initial separation allow for increased resolution. The model is validated for protein migration in both FEF and SDS-PAGE stages of a conventional 2D gel electrophoresis run. Model predictions are verified against two sets of sample proteins. Results from simulations and experiments agree very well for SDS-PAGE. Some discrepancy in the IEF dimension is a constant off-set attributed to the assumption of a linear pH gradient along the IPG strip, and to gel distortion and swelling. This in silica model is successfully used to predict protein migration with traveling wave electrodes.