Novel pressure-sensing skin for detecting impending tissue damage during neuroendoscopy

Abstract

Endoscopy plays an increasingly important role in minimally invasive neurosurgery. Visual feedback from the endoscope tip helps the surgeon prevent unwanted tissue contact. However, critical feedback regarding tissue deformation and trauma from proximal endoscope components is currently unavailable. A system for force feedback along the endoscope length could provide significant clinical benefit by warning of impending damage. The authors manufactured and tested a novel pressure-sensing polymer skin for use in pressure feedback during intracranial endoscopy. A photolithography process on a silicon wafer was used to produce a pattern of 80-μm-tall extrusions to serve as a positive mold for the sensor array. A thin layer of polydimethylsiloxane polymer was molded onto these features. Demolding the polymer from the wafer and sealing with another polymer layer resulted in microchannels. These microchannels were filled with a conductive liquid metal and connected to recording hardware. Spiral channel patterns were designed to create a 3 × 3 array of pressure-sensor pads, which were wrapped around a standard neuroendoscope operating sheath. Pressure readings from the compressed sensor array were translated into a color-coded graphic user interface. Calibration experiments were conducted, and the sensor was evaluated through cortical compression tests on explanted ovine brain. The sensing endoscope operating sheath was successfully calibrated to detect and display pressures within a range consistent with normal and tissue-threatening compressions. Force-feedback mechanisms for the neuroendoscopist are critically lacking with contemporary endoscopes. The authors designed a pressure-sensing skin technology for improved pressure feedback during endoscopy as a means for minimizing collateral tissue damage during endoscopy.