Wearable Body Heat Energy Harvesting

ISEF Category: Energy: Sustainable Materials and Design

Subcategory: Other  ·  Difficulty: Advanced  ·  Setup: University Lab  ·  Time: Full Year

The Hook

Your body gives off heat all day, even when you sit still. A wearable thermoelectric patch can try to catch some of that lost energy. The hard part is predicting how much power you can really get without making the patch uncomfortable. That mix of heat transfer, design, and real-world testing makes this a strong science fair topic.

What Is It?

This project asks a simple question: can you turn body heat into usable electricity with a wearable thermoelectric generator, or TEG? A TEG is a device that makes voltage when one side stays warmer than the other. Think of it like a tiny heat engine with no moving parts. If your skin is the warm side and the air is the cool side, the patch can make power from that temperature difference.

The tricky part is that your body is not a fixed heat source. Skin temperature changes with activity, room temperature, clothing, and airflow. The Pennes bioheat equation is a math model that helps predict how heat moves through living tissue. In this project, you can use Python to simulate skin temperature, then compare your predictions with thermal camera readings from a phone-attachable FLIR camera.

Why This Is a Good Topic

This is a strong science fair topic because you can measure real heat transfer, model it in code, and test whether your model matches reality. You can change patch size, insulation, airflow, or placement and see how each one affects temperature difference and power output. The project connects to wearable tech, energy harvesting, and personal devices that need tiny amounts of power. You can learn modeling, calibration, data analysis, and experimental design without needing a huge lab setup.

Research Questions

• How does patch placement on the body affect the temperature difference across a wearable TEG patch?
• What is the effect of airflow on the power output of a wearable TEG patch?
• Does adding insulation around the patch increase the predicted and measured voltage output?
• To what extent does the Pennes bioheat model match thermal camera measurements on skin under different conditions?
• Which patch size gives the best balance between temperature gradient and skin contact area?
• How does activity level change the stability of power output from a wearable TEG patch?
• What is the effect of ambient room temperature on the efficiency of body heat energy harvesting?

Basic Materials

• Phone-attachable FLIR thermal camera.
• Smartphone or tablet for thermal imaging.
• Wearable thermoelectric generator module.
• Digital multimeter.
• Resistors for load testing.
• Flexible tape or medical adhesive for safe placement.
• Notebook or spreadsheet for logging measurements.
• Laptop with Python installed.
• Room thermometer.
• Small desk fan for airflow tests.

Advanced Materials

• Thermoelectric generator chips with known specifications.
• Data acquisition device with thermocouple inputs.
• Fine-wire thermocouples.
• Infrared emissivity reference tape.
• Heat flux sensor.
• Environmental chamber or temperature-controlled room.
• Flexible substrate materials for patch mounting.
• Heat sink materials in different geometries.
• Open-source circuit board or power management module.
• Body-safe adhesive and insulating foams.

Software & Tools

• Python: Simulates the bioheat model and analyzes temperature and voltage data.
• Jupyter Notebook: Keeps code, plots, and notes in one place for easy revision.
• ImageJ: Measures thermal image regions and compares skin temperature zones.
• Google Sheets: Organizes measurements and makes quick graphs.
• GeoGebra: Helps you check curve fits and simple model behavior before coding.

Experiment Steps

1. Define the one body site and one patch design you will test first.
2. Build a simple Python model of heat flow from skin to air.
3. Choose a way to measure skin temperature and patch temperature under the same conditions.
4. Plan controls that separate body heat effects from room temperature, airflow, and contact quality.
5. Decide how you will convert temperature difference into voltage and power for comparison.
6. Set up a data table that lets you compare model predictions with thermal camera measurements.

Common Pitfalls

• Assuming skin temperature stays constant, which makes the model look better than the real data.
• Measuring thermal images through clothing or reflective tape, which distorts the apparent temperature.
• Letting patch pressure vary from trial to trial, which changes contact resistance and heat flow.
• Using voltage alone without a load test, which hides the real power a TEG can deliver.
• Ignoring ambient airflow, which can dominate the temperature difference more than the patch design does.

What Makes This Competitive

A class-level project measures one patch once and stops there. A stronger project tests several body sites, several environmental conditions, and a clear model against real thermal data. You can stand out by comparing predicted and measured temperature gradients, then using the mismatch to improve the model. A careful uncertainty analysis and a smart load-matching study can push the work much further.

Project Variations

• Test how different clothing layers change the temperature gradient and power output of the same wearable TEG patch.
• Compare skin temperature and TEG output at the wrist, forearm, and upper arm under the same room conditions.
• Use different airflow conditions to see how convection changes the gap between the bioheat model and thermal camera data.

Learn More

• NASA Climate and Earth Science resources: Search NASA for thermal imaging, heat transfer, and surface energy balance background.
• NIH PubMed: Search review articles on thermoelectric generators, skin temperature, and wearable energy harvesting.
• MIT OpenCourseWare: Look for heat transfer and transport phenomena course notes for model-building ideas.
• USGS Water Science School: Use it for clear explanations of energy balance and heat flow concepts in natural systems.
• Journal of Medical Engineering & Technology: Search the journal for articles on wearable thermoelectric devices and skin heat transfer.