A Neuron-Based ISFET Array Architecture with Spatial Sensor Compensation

We present the next step of neuromorphic ISFET arrays with spike domain encoding and spatial device compensation. Each pixel provides a spiking signal with a frequency related to the pH in solution and expected sensitivity of 48.6 to 112.2 kHz/dpH. The array is arranged as clusters which use regulation to cancel undesirable sensor offset and then linear interpolation for temporal drift during the readout. The scheme relies on spatial correlation of ISFET behaviour which is demonstrated with a low standard deviation of 11.6 mV sensor offset, which is well in the pixel compensation range of ± 500 mV. On an array level, address-event representation is used for external signal handling, which enables low power and scalable throughput. The array chip is implemented in TSMC 0.18 μm CMOS technology.