Fiery Hands: Thermal-Tactile Glove for VR Object Manipulation

Fri, 11 Oct 2024 00:00:00 +0000

Overview

How do you make a virtual fire feel real on your hands? Fiery Hands answers that question with a custom wearable thermal glove that delivers localized thermal and tactile sensations to the palm and all five fingertips — without blocking the hand or preventing natural object manipulation in VR.

Published at ACM UIST 2024 (the premier venue for novel interactive systems), this project represents a step change in how XR systems can deliver believable thermal touch.

The Problem

Existing haptic gloves either:

Cover the inner palm and fingertip surfaces, blocking touch and dexterity, or
Place thermal actuators only on the back of the hand, limiting localized feedback

The challenge: thermal actuators are physically large (Peltier modules), slow (seconds to change temperature), and need direct skin contact. Placing enough of them to cover a hand while preserving freedom of movement seemed contradictory.

Research Question: Can we achieve the perception of localized thermal feedback across the full hand using fewer actuators cleverly placed on non-obstructive body sites?

Research Approach

We leveraged two perceptual phenomena from psychophysics:

Thermal Referral — the brain attributes a thermal sensation to a nearby tactile stimulus site, not the actual thermal source. Heat felt elsewhere “moves” to where you’re touching.
Tactile Masking — a vibrotactile cue can suppress or redirect the perceived location of a thermal stimulus.

By combining strategically placed Peltier actuators on the outer palm and back of fingers with vibrotactile motors at fingertip contact points, we could generate perceived thermal sensations at the fingertips without physically touching them.

System Design

Hardware

Thermal actuators: 4 custom-fabricated Peltier modules (30 × 30 mm) mounted on the outer palm and finger dorsal surfaces
Tactile actuators: 5 coin-type LRA vibration motors placed at the inner fingertip
Controller: Arduino Mega with custom power amplifier board; Bluetooth LE to PC
Glove substrate: Thin spandex with 3D-printed actuator mounts — allows full grip

Unity VR Integration

Built in Unity 2022 LTS with OpenXR / XR Interaction Toolkit
Custom C# HapticFeedbackManager subscribes to XR physics collision events and maps contact surface temperature to actuator commands
Real-time thermal rendering: fire = sustained warm + rhythmic vibration; ice = sustained cool + gentle pulse; metal = rapid ramp-up on contact
Deployed on Meta Quest 2 via Quest Link (PC-tethered for full Peltier power budget)

User Evaluation

Study 1 — Thermal Localization

N = 12 participants, within-subject design
Task: identify which finger perceived the thermal stimulus while only the dorsal actuators were active
Conditions: palm-only thermal, 4× Peltier positions × 3 temperature levels (warm/hot/neutral)
Measure: accuracy of localization, JND (just-noticeable difference)

Study 2 — VR Interaction Plausibility

N = 16 participants
Task: interact with three virtual objects (glowing coal, ice block, metal rod) and rate realism
Conditions: thermal-only, tactile-only, thermal+tactile (Fiery Hands), and no-feedback baseline
Measures: NASA-TLX, immersion subscale, perceived temperature match (7-pt Likert)

Results & Key Findings

Localization accuracy: 84% — participants correctly identified the stimulated finger using only dorsal Peltier placement, validating the thermal referral strategy
Plausibility rating of thermal+tactile condition was significantly higher than any single-modality condition (F(3,45)=18.4, p<.001, η²=0.55)
Users reported the coal interaction as “surprisingly convincing” — qualitative themes: warmth buildup over time felt organic, not mechanical
Power consumption reduced by 60% vs. placing individual Peltiers at each fingertip while achieving comparable perceptual quality

Impact

📄 Published: ACM UIST 2024 — Proceedings of the 37th Annual ACM Symposium on User Interface Software and Technology
DOI:
Inspired follow-on work on thermally-integrated wearables for extended wear XR sessions

Fabric Thermal Display: Ultrasound-Heated Wearable for VR

Fri, 01 Sep 2023 00:00:00 +0000

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:
The material findings fed directly into the Fiery Hands glove substrate design and the broader thermal-wearables research program at MI Lab

Wearable | Haokun Wang

Fiery Hands: Thermal-Tactile Glove for VR Object Manipulation

Overview

The Problem

Research Approach

System Design

Hardware

Unity VR Integration

User Evaluation

Study 1 — Thermal Localization

Study 2 — VR Interaction Plausibility

Results & Key Findings

Impact

Fabric Thermal Display: Ultrasound-Heated Wearable for VR

Overview

The Problem

Research Approach

System Design

Ultrasound Setup

Fabric Samples

Glove Design

Unity VR Integration

User Evaluation

Study 1 — Detection Thresholds

Study 2 — Level Identification (Thermal JNDs)

Results & Key Findings

Impact