Flexible Paper Touchpad for Parkinson’s Hand Tremor Detection

Abstract

A resistive touchpad was developed employing paper, pencil graphite, and polydimethylsiloxane (PDMS). A pair of flexible substrates with one side coated with conducting graphite and the other with insulating polymer, were assembled with the help of an intercalated polymer spacer having holes which, allowed the inner graphitic layers of the paper surfaces to come in contact with each other upon touching or pressing. An external electrical circuit was designed to detect the variations in the output electrical resistances. The resistive pad was further modified to develop a point-of-care-testing (POCT) device to detect the hand tremors associated with the neurological disorders such as Parkinson’s disease. The proof-of-concept POCT pad showed variations in the electrical resistance due to the variation in contact area at the inner conductive layers of the paper surface when pressed with a pair of human fingers experiencing tremors. Simplified circuit-models have been discussed to explain the operating principles of the resistive pad and the POCT device. The response from the detection unit helped in evaluating the real time hand tremor levels of patients. The POCT prototype was able to detect the early to chronic stages and severity of tremor and thus is capable of detecting diverse neurological disorders.