Fabric Thermal Display: Ultrasound-Heated Wearable for VR
Overview
Standard thermal wearables rely on Peltier thermoelectric modules — rigid, thick, and power-intensive. Fabric Thermal Display takes a different approach: weave thermally-conductive materials (copper, aluminum mesh) into a fabric glove and excite them with focused ultrasonic waves. The friction heats the conductive fibers, delivering warmth through the fabric itself.
Published at IEEE ISMAR 2023 (IEEE International Symposium on Mixed and Augmented Reality), this project delivers a proof-of-concept for ultrasound-driven textile thermal displays and demonstrates their use in VR object interaction scenarios.
The Problem
Peltier-based thermal gloves work, but they have hard constraints:
- Thickness: modules are 3–5 mm, stiff, and change the hand’s natural shape
- Power: each Peltier draws 3–10 W continuously
- Scalability: covering all fingers requires 5+ modules, complicated wiring, and custom PCBs
Could fabric itself become the thermal actuator — flexible, lightweight, and able to conform to any body shape?
Research Question: Which fabric materials respond best to 40 kHz ultrasonic excitation, and can combinations with conductive materials achieve perceptually meaningful warmth for VR?
Research Approach
We started with a material science study before touching user testing:
- Characterization phase: apply ultrasonic energy to 5 fabric types (polyester, cotton, nylon, Lycra, carbon-fiber blend), measure temperature rise over 30 s at three amplitude levels
- Composite phase: integrate the best fabric (polyester) with copper mesh and aluminum foil, compare thermal curves
- Perceptual phase: user study on thermal detection and level identification with the best material combination
- Application phase: integrate into a glove form factor, demonstrate VR use cases
System Design
Ultrasound Setup
- Ultrasound driver: Ultrahaptics STRATOS board, 40 kHz carrier, amplitude-modulated 0–100%
- Focus geometry: single focal point directed at 15 cm standoff, corresponding to palm contact zone of glove
- Thermal measurement: FLIR A315 thermal camera captured surface temperature maps at 9 Hz
Fabric Samples
| Material | Peak Temp Rise (100% amp, 30s) | Flexibility | Notes |
|---|---|---|---|
| Polyester | +18.4°C | High | Best performance |
| Cotton | +9.1°C | High | Poor — high thermal mass |
| Nylon | +12.3°C | Medium | Acceptable |
| Lycra | +7.8°C | Very high | Too low output |
| Carbon fiber | +21.1°C | Low | Best thermal, too stiff |
Winner: Polyester + Aluminum — +22.6°C peak, flexible, washable
Glove Design
- Polyester base with 0.1 mm aluminum foil laminate on palm zone
- Total glove weight: 28 g (vs. 95 g for Peltier glove baseline)
- No wiring — ultrasound is contactless
Unity VR Integration
- Unity 2021 LTS + Oculus Integration SDK (Quest 2)
- Custom
FabricHapticManager: maps virtual object surface temperature to ultrasound amplitude via lookup table - Demonstrated VR scenarios: picking up hot metal ingot, holding warm beverage, touching cold ice sculpture
- Haptic rendering loop runs at 90 Hz, matching display refresh
User Evaluation
Study 1 — Detection Thresholds
- N = 12 participants
- Task: signal detection (yes/no) across 5 amplitude levels, 2-AFC paradigm
- Measure: warm detection threshold (WDT)
- Result: mean WDT = 38% amplitude (≈ +7.2°C skin surface delta)
Study 2 — Level Identification (Thermal JNDs)
- N = 16 participants
- Task: categorize warmth into 4 levels (none, low, medium, high) from ultrasound-heated glove
- Condition: fabric-only vs. fabric+copper vs. fabric+aluminum
- Result: fabric+aluminum achieved 78% accuracy for 4-level identification, significantly outperforming fabric-only (54%, p<.01) and fabric+copper (66%, p<.05)
Results & Key Findings
- Polyester is the optimal base fabric for ultrasonic thermal generation among tested materials
- Aluminum lamination provides +4.2°C improvement over copper at the same power setting
- Users could reliably distinguish 4 thermal levels through the glove, meeting the threshold needed for meaningful VR thermal rendering
- No participant reported discomfort over 20-minute continuous wear sessions
Impact
- 📄 Published: IEEE ISMAR 2023 — IEEE International Symposium on Mixed and Augmented Reality
- DOI: 10.1145/3489849.3489889
- The material findings fed directly into the Fiery Hands glove substrate design and the broader thermal-wearables research program at MI Lab
