Design of Pressure Sensor Arrays to Assess Electrode Contact Pressure During In Vivo Recordings in the Gut*

The gastrointestinal (GI) tract is in part controlled by slow wave electrical activity. Recordings of slow waves with high-resolution (HR) electrode arrays are used to characterize normal and abnormal conduction pathways. Improving the quality of these electrical recordings is important for developing a better understanding of abnormal activity. Contact pressure is one factor that can affect the quality of electrical recordings. We compared the performance of two pressure sensing devices for measuring HR electrode array contact pressure. A Velostat-based sensor array was custom designed and built in a 4 × 2 conguration (area: 30 mm2 per sensor) to be integrated into electrical recordings. Commercially available FlexiForce A201 sensors were used to compare to the Velostat-based sensors. Benchtop testing of these sensors was performed; the error of the Velostat-based sensors (14−31%) was better than that of the FlexiForce sensors (20−49%) within a range of 2666−6666 Pa. The Velostat-based sensors were also more repeatable than the FlexiForce sensors over the same pressure range. Simultaneous pressure and slow wave recordings were performed in vivo on a rabbit small intestine. The Velostat-based sensors were able to resolve spatiotemporal changes in contact pressure in the range of 0−10 000 Pa.