SoleSignal

SoleSignal presents the design and implementation of a pressure sensitive smart shoe insert capable of detecting intentional foot tap patterns and autonomously triggering emergency alerts through a paired mobile application. The system addresses a critical gap in personal safety technology: the need for a fully hands free, covert emergency signaling mechanism operable across a wide range of high risk scenarios, including medical emergencies, physical altercations, and accident situations. The insert employs force sensitive resistors (FSRs) positioned at the heel and forefoot to capture spatially distributed pressure data. Analog signals are conditioned through a unity gain op-amp buffer stage and sampled via an analog-to-digital converter (ADC) on a Seeed Studio XIAO nRF52840 microcontroller. An exponential moving average (EMA) filter suppresses transient noise, while a multi-parameter detection algorithm evaluates tap count, inter-tap timing, and force magnitude against predefined thresholds to reliably discriminate intentional activation sequences from normal ambulatory activity. Upon successful pattern recognition, the system transmits an alert via Bluetooth Low Energy (BLE) to a companion mobile application, which delivers SMS notifications to designated emergency contacts through the Twilio API, including the user's GPS derived location and activation timestamp. A configurable cancellation window is incorporated post detection to mitigate false alarm rates, and secure one-to-one sensor pairing prevents unauthorized use. A minimal data retention policy ensures user privacy is preserved throughout system operation. SoleSignal demonstrates the viability of embedding intelligent, event driven sensing into everyday wearable form factors to deliver reliable, unobtrusive personal safety capabilities without dependence on manual device interaction.