A tactile sensor ASIC for a sensorized guidewire in minimally invasive surgical operations

In this paper, a tactile sensor ASIC for a sensorized guidewire in minimally invasive surgical operations is presented. This ASIC interfaces with Silicon Nanowire (SiNW) sensors, which capture the force exerted at the tip of the guidewire and present it as a resistance value. The resistance is then converted to current pulses in the ASIC. These pulses are transmitted and displayed on an external monitoring module through a 3-wire interconnect, which is also used to carry the control signals and the power supplies for the ASIC. There are three major challenges: limited area due to the integration at the tip of the guidewire together with the sensors, restricted number of interconnecting wires through the guidewire, and huge resistance variations in the SiNW sensors. These challenges are addressed through an incremental double sampling second-order single-OTA ΔΣ ADC, a 3-wire interface with the external module, and a programmable analog front-end, respectively. The chip has been fabricated in 0.18μm CMOS and occupies an area of only 500μm × 650μm. A 7-bit resolution is achieved for the sensor resistance ranging between 20Ω and 800Ω, with an overall power consumption of only 250μW.