An AlGaN/GaN electrolyte gate field-effect transistor array for the detection of electrical cell signals has been realized. The low-frequency noise power spectral density of these devices exhibits a 1/f characteristic with a dimensionless Hooge parameter of 5 X 10(-3). The equivalent gate-input noise under operation conditions has a peak-to-peak amplitude of 15 muV, one order of magnitude smaller than for common silicon-based devices used for extracellular recordings. Extracellular action potentials from a confluent layer of rat heart muscle cells cultivated directly on the nonmetallized gate surface were recorded with a signal amplitude of 75 muV and a signal-to-noise ratio of 5:1. (C) 2005 American Institute of Physics.