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A MEMS Based In-Silico Cell Electrophysiology Device for Monitoring Transcellular Calcium Currents in Ceratopteris richardii Fern Spores.       A. ul Haque^{1, 2}, M. Rokkam^{1, 3}, A.R. DeCarlo^{1, 2}, S.T. Wereley⁴, S.J. Roux⁵, P.P. Irazoqui⁶, D.M. Porterfield^{1, 2, 6,  1}Bindley Bioscience Center: Physiological Sensing Facility, ²Dept. of Ag. & Bio. Eng., ³Dept. of Elec. & Comp. Eng., ⁴Dept. of Mech. Eng., Purdue University, West Lafayette, IN, ⁵Molecular, Cellular & Developmental Biol., Univ. of Texas, Austin, TX, ⁶Dept. of Horticulture & Landscape Architecture, Purdue University, West Lafayette, IN.

   Gravity is known to direct the polarity of development of Ceratopteris richardii fern spores, and this process involves the activation of a trans-cellular calcium ion current through the individual cells. This has been studied in the past using a self referencing calcium ion probe, but does have inherent limitations in the spatial and temporal resolution of the probe, which has impeded our ability to further study the system. Now we have developed an in-silico Cell Electrophysiology Lab-on-a-Chip device (CEL-C) using advanced micro-fabrication techniques, and this has enabled us to monitor Ca⁺⁺ ionic gradients around multiple fern spores in real time. Each chip has 16 pyramidal pores on it with four Ag/AgCl electrodes leading into them at the four poles. An SU-8 layer is used to insulate the electrodes and the electrodes are coated with a Ca⁺⁺ selective membrane to impart ion selectivity. A custom amplification PCB designed for signal amplification and noise reduction is used to interface the CEL-C device with a 32 channel 18 bit data acquisition unit. A state of the art software, designed in LabView 7.0, allows continuous data measurement and recordings. The CEL-C device has been calibrated and has demonstrated expected Nernstian characteristics with excellent repeatability. Initial ground measurements on the fern spores have been conducted and very promising results have been obtained. While this version of the in-silico CEL-C device has been designed targeting analysis of transcellular ionic calcium currents in Ceratopteris fern spores, the device is actually much more versatile and can be adapted to a variety of cell physiology and other biomedical applications to become an indispensable tool for biology. (Supported by the NASA and the Lilly foundation)  (Supported by NASA: NCC8-242)