Design Day,<\/a> an annual event showcasing students\u2019 solutions to real-world problems.<\/p>\n\n\n\n\u201cThe inspiration for the name came from Baltimore\u2019s nickname, Charm City, and the growing popularity of charms as fashion statements on shoes,\u201d says Batra. \u201c\u2019Chirp\u2019 nods to the device\u2019s alarm sound and the university\u2019s Blue Jay mascot.\u201d<\/p>\n\n\n\n
The device is powered by piezoelectric energy generated through walking or other movement, minimizing the need for frequent charging and increasing reliability in critical moments.<\/p>\n\n\n\n
When activated by a vigorous stomp, the alarm emits a distinct sound that reaches up to 100 decibels\u2014about the volume of a car horn or your average rock concert.<\/p>\n\n\n\n
\u201cIts purpose is to draw attention quickly and potentially deter an attacker,\u201d says Peixoto.<\/p>\n\n\n\n
The device attaches to the top of a shoe using two lace holes, with a thin piezo pad resting inside. A strong stomp or kick activates a “Listening” mode, indicated by a vibration. If a second stomp occurs within 20 seconds, a 104 decibel alarm is triggered; otherwise, the device resets automatically. A small side button on the external charm allows users to exit Listening mode or silence the alarm at any time, whether the initial stomp was accidental or the user no longer feels at risk.<\/p>\n\n\n\n
\u201cWe chose a stomp because it reflects a natural panic response,\u201d explains Ji. \u201cThe motion sensors in the device detect this specific foot movement, helping ensure the alarm activates only when needed.\u201d<\/p>\n\n\n\n
The team faced several technical hurdles as they developed the device. Early piezoelectric components failed to produce consistent energy, leading to a switch to specialized energy-harvesting models. The stomp-based trigger also required careful calibration to balance usability and efficiency.<\/p>\n\n\n\n
Speaker selection posed another challenge.<\/p>\n\n\n\n
\u201cWe experimented with various models and are now working on a custom acoustic case to boost the alarm\u2019s volume,\u201d says Phillips. \u201cThe new design creates a distinct siren sound that stands out from typical alarms.\u201d<\/p>\n\n\n\n
Ultimately, the project reflects a thoughtful blend of engineering and user-centered design.<\/p>\n\n\n\n
\u201cOur goal was to create something subtle but powerful,\u201d says Batra. \u201cWhether you’re walking through a busy city or traveling alone, we wanted our device to be a very simple way to feel more secure without having to think twice about it.\u201d\u00a0<\/p>\n\n\n\n