💪 Overview
Manual Muscle Testing (MMT) is a standard clinical tool for evaluating muscle strength. But for all its use, it’s surprisingly subjective—usually scored on a 0–5 scale based on a clinician’s feel. At Shirley Ryan AbilityLab, we set out to modernize this process by creating a wireless, handheld device that could deliver objective, quantifiable measurements—and display the results in real time.
This project challenged me to bring together embedded hardware, user-centered design, mobile UI development, and cloud backend integration—all in a single device clinicians could use right out of the box.
🎯 Objectives
We wanted to create a system that:
- Could measure muscle force with precision using a load cell,
- Was handheld, wireless, and ergonomic for daily clinical use,
- Displayed and logged results in real time,
- Allowed for longitudinal tracking and comparison across patient visits, and
- Could one day integrate directly with EMR systems.
I owned the full stack, from hardware to mobile app to backend, and iterated closely with clinicians throughout the process.
⚙️ What I Built
- Embedded Hardware:
- Designed and built a two-sided PCB shield with:
- Load cell amplifier and ADC interface
- Power conditioning and battery charging circuit
- Multicolor LED indicators for connection and test status
- BLE antenna and microcontroller interface (via MicroPython)
- Integrated the PCB into a fully enclosed ergonomic handheld device.
- Firmware Development:
- Wrote BLE communication routines and implemented a finite state machine for test start, data collection, and upload.
- Tuned data acquisition to match clinical timing constraints and reduce noise.
- Mechanical Design & Fabrication:
- Prototyped multiple handheld enclosures to balance usability, ergonomics, and strength.
- Machined parts in-house and revised geometry based on hands-on clinician feedback.
- Mobile App (Unity C#):
- Built a companion Android app that:
- Connected to the device via BLE
- Displayed real-time force graphs and test status
- Allowed for patient login and session management
- Compared current results with past visits via overlay visualization
- Cloud Backend (GCP + MySQL):
- Logged force data and session metadata to the cloud for later retrieval and analysis.
- Created secure patient-level tracking with time-stamped session history.
- Clinical Engagement:
- Demoed the system live to over 80 clinicians and researchers.
- Incorporated feedback to improve grip ergonomics, app UI, and test flow.
- Participated in meetings with hospital tech teams to assess EMR integration feasibility.
✅ Outcome
The device successfully delivered real-time, quantitative muscle strength assessments with intuitive user interaction. It was well-received by clinicians, especially for its ability to overlay test results and track patient progress over time.
This project not only proved that low-cost digital muscle testing was viable—it also created a platform that could extend into future clinical tools, including integration with hospital records or expansion to related assessments like spasticity or fatigue.
It was a deeply rewarding project where I was able to wear every engineering hat—from circuit design to app development to user testing—and build something that could directly impact patient care.