A novel device for studying temperature and touch interactions.

Abstract

Background: Existing methods to study the effects of skin temperature on mechanical touch perception range from large hot plates, water baths, or bulky, water-controlled thermal contactors which have limited range and resolution. The limited capabilities of these methods prevent the study of thermo-tactile interactions at the finger level in a flexible and precisely controlled manner.

New method: Here, we combine small Proportional-Integral-Derivative (PID)-controlled Peltier elements with a calibrated shaker motor for a novel thermo-tactile stimulus delivery system capable of precisely controlling temperature and vibrotactile stimulation to the fingertip. This novel system enables parallel control of mechanical stimulation and thermal stimulation at congruent skin sites of the fingertip. Alternative thermoelectric elements and mechanical actuators could be used in our systems modular configuration.

Results: Our thermo-tactile delivery system can simultaneously deliver precise and stable vibrotactile and thermal stimuli over 30-250 Hz and 20-40°C, respectively, at the fingertip. We validated our system in psychophysical tests and reproduced the established finding that vibration detection thresholds vary according to temperature.

Comparison with existing method(s): Unlike our system, existing methods to study thermo-tactile interactions are restricted to testing skin regions larger than the fingertip or they use tactile probes on the fingertips that are not thermally controlled.

Conclusions: Our system represents a novel strategy for combining thermoelectric modules with mechanical actuation to study thermo-tactile interactions at mechanoreceptor-rich fingertips.