Live Demonstration: A Soft Thermal Modulation System with Embedded Fluid Channels for Neuro-Vascular Assessment

Abstract

This live demonstration presents a wearable system for neuro-vascular health assessment. The system is comprised of three key subcomponents: 1) a soft, fluid-driven thermal modulation pad, 2) a portable case containing electrical and mechanical hardware, and 3) off-board biosignal processing and power units. The soft thermal modulation pad (the only component that interfaces with the user) contains fluid channels, embedded temperature sensors, and a flexible protoboard, encased in graphite-based silicone. The pad induces fluid-based heating or cooling of the hand, and is connected to the portable case through inlets and outlets. The portable case contains electrical and mechanical actuation (temperature modulation, fluid flow), sensing, and control circuitry, none of which is in contact with the user. Components include Peltier tiles, temperature and flow rate sensors, fluid pump, reservoir, control circuitry, heat sinks, cooling fans, and a microcontroller. All components in the case are enclosed with a laser-cut acrylic sheet to shield them from outside world, except for the fluid reservoir (to be filled with water before use) and toggle switches. Separate from the portable case and the pad are a data acquisition system, photoplethysmography (PPG) sensor to be worn on the hand, a laptop for visualization of the data, and a power supply. To enable closed-loop temperature control, the current and voltage flowing through the Peltier tiles are controlled with a custom algorithm implemented on the microcontroller. Biosignals involved with thermoregulation are collected. PPG measures the changes in blood volume pulse at the collected location; the amplitude of the PPG signal reflects the change in dilation or constriction of the vasculature [1].