Towards the development of a MEMS-based force sensor for in vivo tumor tissue demarcation

Surgical resection is one of the primary treatments for patients with brain tumors. The precise detection of tumor tissue margin during the resection procedure ensures safe maximal removal of the tumor tissue while protecting the surrounding healthy, functional tissue. Micro-electro-mechanical-system (MEMS)-based sensors with high sensitivity and small footprint can enable reliable intraoperative in vivo tumor margin assessment, quantitatively distinguishing between normal and abnormal tissue. In this paper, we present the design of a MEMS-based piezoresistive force sensor integrated into a steerable robotic probe. The sensor design optimization, microfabrication process flow, and packaging methodology are presented. The characterization process of the diaphragm-based piezoresistive sensor using a commercial force sensor and an indentation system is described. The sensor can measure forces in the range of 0-0.3N, and the packaged sensor is within 2 mm diameter. The sensor's output shows a linear response with force, and the sensor has a maximum hysteresis of 5.58 %.