This award supports the development of integrated patch-clamp instrumentation for recording the electrical potential of individual cell membranes with higher sensitivity and throughput. This instrumentation will allow measurements of the opening and closing of individual ion-channels whose conductance has previously been too low to measure. Integrated circuitry will be developed to increase the density of recording sites and miniaturize the recording equipment. The circuit design will feature the silicon-on-sapphire technology. This integrated-circuit technology provides low-noise amplification of ion-channel currents and high-density integration of electronic components. An integrated patch-clamp amplifier will give better electrical performance, due to the reduction of cabling and parasitic capacitances that lower the measurement sensitivity.
This project will advance the understanding of ion channels, fundamental components of living cells. Using the proposed instrumentation, it may be possible to characterize the function of the products of the approximately 400 ion channel genes. The PIs are involved in CPEP: the Connecticut Pre-Engineering Program for under-represented minority and women students. Within this program, the PIs are working with children and teachers from K to 12, to promote practical science projects and to develop interest, abilities and communication skills. The PIs excite students' interest through presentations in local schools, participation to the New Haven Science Fair, and organizing laboratory tours and weekend science projects.
The original goal of this award was the development of integrated instrumen- tation used for recording the electrical potential of individual cell membranes. The patch-clamp amplifier is a ubiquitous tool for characterizing ion-channel activity. For the screening of pharmaceutical compounds or the characterization of expressed channels, high-throughput patch-clamp systems are being devel- oped, where recordings are made from cells in each well of a 96 or 384-well plate. An important part of such highly-parallel recording systems is a high-density array of patch-clamp amplifiers. In the context of this proposal, we designed a highly-miniaturized patch-clamp amplifier with complete whole-cell measurement capabilities. Important constraints in building massively-parallel patch-clamp systems have been the size and cost of the amplifiers, heat dissipation - which restricts the proximity of the amplifiers to the cells - and crosstalk between channels. The integrated "PatchChip" amplifier presented here solves all of these design requirements, and is based on experience from our prototypes. The dual-channel patch-clamp system occupies 3mm x 3 mm of area and consumes just 5 mW of power per channel. It is fabricated using a standard silicon-on- sapphire fabrication process, which allows parasitic capacitances and cross-talk effects to be minimized. The target is an improvement of both sensitivity and throughput of current patch-clamp instruments for ion-channel research and the patch-clamp method, currently the most widely used method for this purpose.By reducing patch-clamp amplifiers to a millimeter size micro-chip, this work paves the way to the real- ization of automated, high-throughput patch-clamp systems for drug screening and ion-channel research. This project has been very successful. Our original goals have all been met and we designed the first, fully-integrated, two-channel implementation of a patch- clamp measurement system. With system two simultaneous whole-cell recordings can be obtained with low recording noise. The capacitance and series-resistance of the patch-clamp electrode can be compensated under computer control. Recordings of current in real biological cells demonstrated the system’s capabilities, which are on a par with large, commercial patch-clamp instrumentation.
