Skin-Like Material Protect Tissues During Endoscopy Procedures

A photolithography process on a silicon wafer was used to produce a pattern of 80-μm-tall extrusions as a positive mold for the sensor array. A thin layer of polydimethylsiloxane polymer was then molded onto these features. Separating the polymer from the wafer and sealing it with another polymer layer resulted in the creation of microchannels, which were filled with a conductive liquid metal.

The microchannels were formed into spiral channel patterns, creating a 3 × 3 array of pressure-sensor pads, which were then wrapped around a standard neuroendoscope operating sheath. The pressure readings from the compressed sensor array were then recorded and translated into a color-coded graphic user interface, attuned 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. The study was published in the January 2014 issue of Journal of Neurosurgery: Pediatrics.

“The capability to monitor the pressures applied along the surface of a surgical instrument could provide critical feedback to the surgeon about impending collateral damage, and so enable avoidance of this damage as the operation is carried out,” said senior author Pierre Dupont, PhD, chief of pediatric cardiac bioengineering. “In our experimental phase, we recognized the value in the fact that if you can’t see it, you can still feel it. In assessing how much pressure is ‘bad,’ we estimated that damage will begin to occur to tissue at about 30 mm of mercury, based on a review of the modest literature available on the topic.”

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. The new sensing “skin” can provide color-coded visual cues of graded feedback, proportional to the applied pressures. Alternative feedback modalities, such as auditory or tactile feedback, could reduce the cognitive load on the clinician and improve performance.

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