Electrical Stimulation, Recording and Impedance-Based Real-Time Position Detection of Cultured Neurons Using Thin-Film-Transistor Array

A novel thin-film-transistor (TFT)-based microsystem array derived from flat panel technology has been developed for functional extracellular neural stimulation and recording. These arrays are microfabricated to meet the needs of optical transparency and extremely high density of electrodes with a large sensor area over 25 mm x 27 mm. Indium tin oxide has been used for surface electrode fabrication with the pitches of 50 and 100 μm and an optical transparency of ~95%. Each individual electrode is controlled through transistor drain voltage. The array consists of 30000 transistors over 243.75 mm2 chip area. The device has an extra extra high dot per inch (extra extra high density) resolution of 359.2 PPI (pixels per inch) or 7.07 x 10-4 mm dot pitch. The durability of the stimulated electrodes is extremely high, lasting more than one billion pulses without failure in dry as well as wet environments. Primary neuron cell cultures were established inside the polydimethylsiloxane chamber on the TFT substrate. Extracellular electrical signals were successfully recorded for both the currentand voltage-type stimulations. The binary presence of cells in a given region was achieved by means of impedance measurement.