The development of Project Aegis was not a series of aesthetic guesses, but a rigorous integration of STEM principles to address a high-stakes human-safety crisis. To move from a conceptual wearable to a functional lifeline for survivors, we anchored our process in Science, utilizing electromagnetic wave propagation and human physiology to understand how a device behaves under the physical and biological stress of an emergency. This scientific foundation was realized through Technology, specifically the synchronization of Global Navigation Satellite Systems (GNSS) and cellular communication with a custom-built Firebase database. The physical manifestation of these ideas required Engineering precision, moving from 3D-modeled enclosures to complex mechatronic systems and hand-soldered PCB assemblies. Finally, Mathematics provided the validation for every design choice, from spherical trigonometry for location accuracy to algebraic power modeling that ensures the device never dies when it is needed most.

 Domestic abuse victims often face significant barriers when seeking help. Even if they have some mobility,  71% of victims' report that abusers monitor their communication, restrict their movements, and/or manipulate them in a manner that prevents them from reaching out in an indiscreet manner. Current safety tools are either too visible, inflexible, or too dependent on established infrastructure or law enforcement, leaving victims without discreet, reliable, and comfortable ways to signal for help. 

Science

Human Physiology and Stress Response

We consulted several clinical psychologists for the idea generation of one of our initial prototype concepts, as well as a police officer who specialized in the domestic violence unit. Competitive analysis revealed that traditional emergency response systems, such as LifeAlert, often fail in domestic high-stress scenarios due to the psychological friction associated with high-visibility triggers. Research indicates that the 'imposing' nature of a large, red button can induce a sense of decision paralysis or guilt in victims of domestic abuse, who may be conditioned to avoid overt 'confrontational' actions. Project Aegis addresses this by utilizing a discreet, low-profile interface that lowers the cognitive threshold required for a user to seek intervention. Our initial prototype design mimicked the design of an eco-map—a map of a person's or family’s social network, relationships, and environmental interactions that is commonly used in counseling sessions. The intended design was to have each bead represent a certain social facet. However, we scrapped the idea of a beaded bracelet due to its complex use, opting for a single button with customizable combinations.

Technology

Engineering

3D Modeling

We utilized Autodesk Fusion 360 to develop a comprehensive 3D model of the Project Aegis hardware stack. This process involved creating custom components for the ESP32, SIM7080G module, and haptic drivers and placing them in a manner that maximized spatial efficiency on our perfboard. The modeling phase was critical for identifying a layout that would be most optimal for soldering while maximizing antenna exposure.

Mechatronics

Math

Power Consumption Modeling

To select an appropriate power source for Project Aegis, we performed a power budget analysis. By aggregating the peak current draws of the SIM7080G (500mAh) and the ESP32 (80mAh), we determined a maximum load of approximately 600mAh. Factoring in a 90% efficiency rating for the TPS63020 buck-boost converter, we calculated that a 3.7V LiPo battery rated 800mAh would provide a functional runtime of ~6 hours. In a sustained Emergency Alert state—incorporating cellular transmission and haptic feedback—the device provides nearly one hour of continuous SOS broadcasting. This balance of capacity and current draw demonstrates the device's ability to provide protection throughout a standard commute or outdoor activity while maintaining a compact, wearable form factor. Incorporating ESP32 "Deep Sleep," which means waking it up every 5 minutes to check the location instead of constant tracking, in combination with GPS duty cycling, which means immediately turning off the GPS once a location is stored, pushes our runtime to over 24 hours. Equations used include the Power Summation Law, the Power Conservation Law, the Usable Capacity Equation, and Peukeurt's Law.

Spherical Trigonometry and Geofencing

The intelligence of Project Aegis is rooted in Geospatial Mathematics. By implementing the Haversine Formula, the GPS automatically calculates the great-circle distance between the user and predefined safe coordinates, accounting for the Earth's curvature to ensure meter-level accuracy. This data feeds into our Geofencing Logic, which utilizes radial inequalities to monitor the user's position relative to safety perimeters. This mathematical framework allows the device to make autonomous decisions—such as transitioning from low-power standby to active monitoring—based on the user's real-time proximity to designated 'Safe Havens'. In hardware terms, the system increases the rate at which the GPS samples coordinates outside of, say, your home.

RSSI Calculations

To ensure the reliability of emergency transmissions, Project Aegis performs real-time RSSI (Received Signal Strength Indicator) calculations. By measuring the incoming signal power on a logarithmic decibel-milliwatt (dBm) scale, the system can quantify the 'Link Budget' available between the wearable and the nearest LTE-M cellular tower. This mathematical evaluation is critical for adaptive broadcasting: if the RSSI falls below a critical threshold (typically -100 dBm), the device's logic-level mapping triggers a higher-power transmission mode or alerts the user via haptic feedback that they are entering a 'dead zone.' This ensures that the user is never left with a false sense of security in areas where electromagnetic propagation is insufficient for a life-safety alert.

The integration of these STEM principles serves as the ultimate validation of our problem statement: that personal safety requires a discreet, reliable, and scientifically grounded intervention. By applying human physiology to the design, I substantiated the need for a haptic-feedback wearable and the appeal of a discreet panic button design. Our design decisions were never arbitrary; they were strictly dictated by the mathematical limits of signal reliability and the engineering constraints of miniaturizing a mechatronic system into a ring form factor. Additionally, we didn't just pick a random ring size; the dimensions were mathematically forced by the physical volume of the ESP32 and the haptic motor. We didn't guess if the battery would last; we used power consumption modeling to prove that an 800mah 3.7V lithium polymer battery was the most viable option. We ensured that the probability of a message failing was low enough to be trusted via signal reliability calculations.