TITLE: Integrated Circuits and Hardware Design for Strain Sensor Measurement using Time-Domain Reflectometry

ABSTRACT: Strain sensors are critical components that enable shape reconstruction in the growing fields of soft robotics and wearable electronics. This work presents a strain-sensing method utilizing time-domain reflectometry (TDR), which overcomes the non-linearity and complex calibration of traditional resistive strain sensors. The sensors are constructed as stretchable transmission lines, made from liquid metal paste conductors encapsulated in silicone, on which we make our time-of-flight measurements. Picosecond-scale time conversion is achieved with a dual-slope time-to-digital converter (TDC) implemented in 180 nm CMOS technology. The TDC achieves an 11.1 ps resolution, enabling milllimeter-scale length sensing. We further introduce an iterative measurement architecture proposed for multi-segment strain, allowing readout of multiple lengths from a single sensor. Results demonstrate that these TDR-based sensors are highly linear, and they eliminate the need for bulky, expensive bench-top TDR equipment.

MAJOR ADVISOR: Matthew Johnston
COMMITTEE: Un-Ku Moon
COMMITTEE: Joseph Davidson
COMMITTEE: Arun Natarajan
GCR: Matthew Graham