Screen-Printed Resistive Tactile Sensor for Monitoring Tissue Interaction Forces on a Surgical Magnetic Microgripper

With the recent development of novel miniaturized magneticallycontrolled microgripper surgical tools (of diameter 4 mm) for robot-assistedminimally invasive endoscopic intraventricular surgery, the surgeonloses feedback from direct physical contact with the tissue. In thiscase, surgeons will have to rely on tactile haptic feedback technologiesto retain their ability to limit tissue trauma and its associatedcomplications during operations. Current tactile sensors for hapticfeedback cannot be integrated to the novel tools primarily due tosize limitations and low force range requirements of these highlydextrous surgical operations. This study introduces the design andfabrication of a novel 9 mm(2), ultra-thin and flexible resistivetactile sensor whose operation is based on variation of resistivitydue to changes in contact area and piezoresistive (PZT) effect ofthe sensor's materials and sub-components. Structural optimizationwas performed on the sub-components of the sensor design, includingmicrostructures, interdigitated electrodes, and conductive materialsin order to improve minimum detection force while maintaining lowhysteresis and unwanted sensor actuation. To achieve a low-cost designsuitable for disposable tools, multiple layers of the sensor sub-componentwere screen-printed to produce thin flexible films. Multi-walled carbonnanotubes and thermoplastic polyurethane composites were fabricated,optimized, and processed into suitable inks to produce conductivefilms to be assembled with printed interdigitated electrodes and microstructures.The assembled sensor's electromechanical performance indicatedthree distinct linear sensitivity modes within the sensing range of0.04-1.3 N. Results also indicated repeatable and low-timeresponses while maintaining the flexibility and robustness of theoverall sensor. This novel ultra-thin screen-printed tactile sensorof 110 & mu;m thickness is comparable to more expensive tactilesensors in terms of performance and can be mounted onto the magneticallycontrolled micro-scale surgical tools to increase the safety and qualityof endoscopic intraventricular surgeries.

Automated summary

With the development of miniaturized magnetically-controlled microgripper surgical tools, tactile haptic feedback technologies are required to limit tissue trauma. However, current tactile sensors cannot be integrated due to size limitations. This study introduces a novel thin and flexible resistive tactile sensor that shows promising electromechanical performance and can be mounted onto surgical tools to improve safety and quality of endoscopic surgeries.