Extending the Senses of Ubiquitous Devices

Abstract

Modern smart devices come equipped with a wide array of sensors, many of which can be repurposed for functionalities beyond their original intent through side-channel sensing. While this technique offers innovative uses without altering hardware, the enhancements it provides are often modest. In contrast, incorporating new hardware can dramatically expand a device's capabilities but entails significant costs and lengthy redesign cycles. This thesis investigates two strategies to bridge this trade-off, aiming to unlock the full potential of side-channel sensing on existing platforms. The first strategy involves user-friendly, low-cost, low-power sensor add-ons that enhance device functionality without requiring internal hardware changes. The second strategy targets manufacturers, proposing selective hardware upgrades to improve performance with minimal cost and development overhead. To demonstrate the efficacy of these approaches, the thesis presents several real-world applications: a smartphone-based glucose testing add-on for accessible at-home pre-diabetes screening; a toolkit to streamline the development of rapid diagnostic test attachments; a versatile, energy-efficient sensor platform for smartwatches that supports integration of external sensors; and targeted hardware enhancements—such as increased bio-impedance sensing bandwidth in rings and wristbands—that enable richer contextual interactions and novel input methods. These research projects demonstrate the practical viability and versatility of augmenting side-channel sensing through both user-centric and manufacturer-driven enhancements. The thesis concludes by outlining how strategic improvements to existing devices can democratize access to advanced sensing technologies and inform future research and design in ubiquitous computing.