Microfabrication of PMMA sensor chips for an incubation-type planar patch clamp

A sensor chip for use in an ion channel biosensor based on an incubation-type planar patch clamp was formed using both side hot embossing and focused ion beam (FIB) processing. A biosensor was constructed using the PMMA chip, and the performance of this chip was investigated by measuring the laser-stimulated ion channel current of a channel rhodopsin wide receiver (ChRWR) expressed on HEK293 cells. The observed current profile and membrane potential dependences agreed well with the data measured using a pipette patch clamp. The noise level of the channel current recorded using a 1 kHz low pass filter was 7 pA (rms). The sensor chip fabrication processes are readily modified to permit multi-point measurements; therefore, the excellent performance of the PMMA chip indicates that the chip is suitable for use in high-throughput ion channel biosensor screening applications.