Matt Strong

Matt Strong

CS PhD at Stanford University

← Paper Digest

A Multimodal Haptic Interface for Simultaneous Softness and Thermal Modulation

Joshua Brown, Fernando Bello, Lynette Jones

November 2026

TL;DR A desktop tactile display that changes both softness, by twisting a pouch of granular particles until they jam, and temperature, by pumping Peltier-heated or cooled water through a silicone skin. Stiffness rises from 0.63 to 2.38 N/mm, the surface spans 9.3 to 50.2 °C, and closed-loop control holds a setpoint within ±0.2 °C.

What they do

Most tactile displays render one cue at a time. This paper builds a 150 mm round display that renders softness and temperature together. A particle-jamming core sets stiffness, and a thin silicone skin carrying heated or chilled water sets the surface temperature. Both channels are characterized with bench measurements; no user study is reported.

How it works

  • Softness. Constrictive jamming: particles in a fabric pouch are twisted from one end by a brushless motor under closed-loop torque control, so more torque means a stiffer surface. No pump or airtight container is needed.
  • Temperature. Water flows through channels cast in silicone under a touch layer of silicone mixed 60:40 with copper powder to spread heat. The plain silicone insulates the jamming core. A 100 W Peltier module heats or cools the water.
  • Control. An Arduino uses bang-bang control when the temperature is more than 5 °C from the setpoint and PID inside that band, with thermistors under the skin.

Results

  • Stiffness, measured with an 8 mm indenter over 0.5-1 N, rises linearly from 0.63 N/mm (unjammed) to 2.27 N/mm at 0.5 Nm of torque, then levels off at 2.38 N/mm at 1 Nm. Hysteresis falls from 84% to 2.1%.
  • At full power the surface reaches 50.2 °C in 20 minutes (τ = 290 s) and cools to 9.3 °C (τ = 325.5 s). Neighboring channels differ by under 0.3 °C, and the pouch exterior stays at 26 °C when the surface is above 50 °C.
  • Commanded from about 33 °C to 15 °C, it took 12 minutes, then held within ±0.2 °C for 15 minutes.

Limitations

Temperature changes are slow: every test showed a 30 s lag between command and response, and reaching the maximum took 20 minutes, which the authors attribute to the Peltier module and the fluid’s thermal mass. The closed-loop test was preliminary, and recovery from perturbations was not tested.

Figures

From Figure 1: Schematic of the mechanical and hydraulic components of the combined softness and temperature display....
From Figure 1: Schematic of the mechanical and hydraulic components of the combined softness and temperature display. Inset: the underside of the cast silicone skin with its fluid channels.
From Figure 2: Apparatus used to measure initial contact stiffness (left) and temperature (right).
From Figure 2: Apparatus used to measure initial contact stiffness (left) and temperature (right).
From Figure 3: Stiffness and hysteresis of the display under different motor torques. Error bars show the highest and...
From Figure 3: Stiffness and hysteresis of the display under different motor torques. Error bars show the highest and lowest values across repeated measurements.
From Figure 4: Surface temperature over time with heated and chilled water.
From Figure 4: Surface temperature over time with heated and chilled water.
Abstract

Haptic interactions, such as touching an object in virtual reality, involve detecting a plethora of sensations through the skin. Whilst tactile displays exist to simulate and manipulate all of these cues individually, little progress has been made constructing devices that can control multiple cues simultaneously. This paper presents a tactile display technology that offers both softness and temperature change. A prototype display, based on particle jamming and the thermal transfer of heated and cooled water, is evaluated in terms of its ability to change both stiffness and temperature. Mechanical evaluations demonstrate controllable stiffness increase of 300%, whilst thermal characterisation showed strong surface uniformity and a range of achievable temperatures from 10°C up to 50°C, with closed-loop control maintaining a ±0.2°C error from a setpoint. This work advances the design of multimodal tactile displays with applications to perceptual research, medical simulation, and affective haptics.

Summaries are written automatically from each paper's text. Figures and videos come from the paper and its project page; all credit goes to the authors.