Interview Questions › Product Design

Design a mobile and haptic companion app for a smart bionic prosthetic limb

Design a mobile configuration app, EMG sensor muscle calibration system, and sensory feedback companion for amputees using advanced multi-grip smart bionic prosthetic hands.

Context

Bionic prosthetic hands are complex to calibrate, muscle signals change throughout the day as the stump swells or sweats, and amputees lack sensory feedback (cannot feel how hard they are gripping a glass).

Clarifying questions to ask first

• How does the prosthetic communicate with the app (Bluetooth Low Energy)? (Yes).
• How are grip patterns changed on the fly? (Muscle double-pinch gesture or quick smartphone widget).

How to approach it

1. Amputee User Journey & Frustrations: Muscle fatigue when triggering grips, accidental crushed soda cans due to zero sensory feedback, frustrating manual calibration, stump skin friction and battery anxiety
2. Design Bionic Companion Ecosystem:
3. 1. 1-Tap Grip Pattern Customizer & Quick Switcher ("Power Pinch", "Key Grip", "Keyboard Typing Mode" with NFC wrist gesture shortcuts)
4. 2. AI "Adaptive Muscle Signal Calibration" (Gamified 2-minute daily training game that recalibrates EMG sensors to adjust for muscle fatigue and sweat)
5. 3. Haptic Sensory Feedback Loop (Prosthetic fingertip pressure sensors send gentle vibration pulses to the upper arm so user 'feels' grip tightness)
6. 4. Battery Longevity & Motor Health Telemetry

Framework: Amputee Physical Challenges -> Grip Customization & Fast Switching -> AI EMG Muscle Calibration -> Sensory Feedback Mechanism -> Quality of Life Metrics

Sample answer

• Muscle EMG signals drift as the user sweats during the day; a 60-second adaptive calibration game prevents frustrating grip misfires
• Haptic feedback on the remaining limb allows the user to hold delicate objects without looking directly at their hand

1. MVP: Visual grip selector library, gamified EMG muscle calibration tool, haptic grip pressure visualizer, and maintenance/battery health alerts

Executive design: A bionic prosthetic companion app featuring instant custom grip switching, gamified EMG muscle signal recalibration, and sensory haptic grip feedback.

What interviewers look for

• Amputee Daily Ergonomics & Grip Customization
• Gamified EMG Muscle Signal Calibration
• Sensory Pressure Feedback Loop (Haptic upper-arm mapping)
• Prosthetic Reliability & Battery Safeguards