Triboelectric Incontinence Sensor
ISEF Category: Biomedical Engineering
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Subcategory: Biomedical Devices · Difficulty: Advanced · Setup: Home Setup · Time: 1 to 2 Months
The Hook
Pelvic floor dysfunction affects millions of women but most go undiagnosed. A self-powered sensor that detects both wetness and pressure inside a regular panty-liner could screen people years earlier. Aluminum foil, Velostat, and a PVDF film harvest the energy themselves and beam alerts to a phone over Bluetooth.
What Is It?
Triboelectric generators produce small voltages when two materials separate and contact. PVDF is a piezoelectric polymer that adds pressure sensitivity. Velostat is a conductive foam used as a pressure layer.
The combined sensor sits inside a panty-liner. When pressure changes (cough, sneeze, leak), the sensor produces voltage spikes whose pattern differs from baseline. A small ESP32 reads the signal and transmits over BLE.
The fusion of wetness (capacitance change) and pressure (triboelectric spikes) gives a screening signal for stress incontinence and pelvic-floor weakness. Real diagnosis still requires a clinician.
Why This Is a Good Topic
Self-powered wearable sensors are a growing field. Materials are cheap and the use case is real. You will learn material physics, low-noise sensor design, and embedded BLE.
Research Questions
- How does layer thickness change triboelectric voltage amplitude?
- What is the effect of fluid volume on capacitance shift?
- Does the fused signal outperform single-modality baselines?
- To what extent does fabric backing affect output?
- Which event type triggers the largest fusion spike?
- How does body motion noise contaminate the signal?
- What is the effect of BLE transmit interval on battery life?
Basic Materials
- Aluminum foil.
- Velostat conductive foam.
- PVDF film (small online sample).
- ESP32 with low-power mode.
- Coin-cell or LiPo battery.
- Simulated fluid (saline) and test rig.
- Informed-consent form.
Advanced Materials
- Polished PVDF or PTFE sheets.
- Lab-grade capacitance meter.
- Anechoic shielding chamber.
- Clinical mentor.
Software & Tools
- Arduino IDE or PlatformIO: Programs the ESP32.
- Python (NumPy): Processes the captured signal traces.
- nRF Connect: Verifies BLE transmissions.
- Matplotlib: Plots event-classification confusion matrices.
Experiment Steps
- Build a controlled fluid-volume rig before any wear test.
- Decide layer stack-up and lock dimensions.
- Calibrate output voltage vs. known pressure events.
- Plan controls (no fluid, no pressure) and randomized order.
- Combine modalities in software and tune fusion thresholds.
- Report detection accuracy under motion noise.
Common Pitfalls
- Mixing layer materials between trials.
- Letting humidity drift, which changes triboelectric output.
- Ignoring electromagnetic interference from phones.
- Treating one test cycle as full data.
- Skipping a safety review for body-contact materials.
What Makes This Competitive
A competitive project shows a clear signal-to-noise comparison against a single-modality baseline, calibrates voltage signatures with a benchtop fluid setup, and reports detection accuracy under realistic body-motion noise. Informed-consent and material-safety reviews are essential.
Project Variations
- Replace PVDF with a homemade nanofiber mat.
- Add a thermistor for warmth-related leakage detection.
- Test the sensor under simulated diaper-pad geometry instead.
Learn More
- PubMed: Search triboelectric wearable health sensor reviews.
- NIH PubMed Central: Open-access incontinence screening papers.
- Espressif ESP32 documentation: Free hardware guides.
- ASTM International: Standards on absorbent garment testing.
- MIT OpenCourseWare: Course 6.S191 Introduction to Deep Learning.
Biomedical Engineering pillar guide
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