Advanced approaches for quantitative characterization of thermal transport properties in soft materials using thin, conformable resistive sensors

Abstract

Noninvasive methods for precise characterization of the thermal properties of soft biological tissues such as the skin can yield vital details about physiological health status including at critical intervals during recovery following skin injury. Here, we introduce quantitative measurement and characterization methods that allow rapid, accurate determination of the thermal conductivity of soft materials using thin, skin-like resistive sensor platforms. Systematic evaluations of skin at eight different locations and of six different synthetic skin-mimicking materials across sensor sizes, measurement times, and surface geometries (planar, highly curvilinear) validate simple scaling laws for data interpretation and parameter extraction. As an example of the possibilities, changes in the thermal properties of skin (volar forearm) can be monitored during recovery from exposure to ultraviolet radiation (sunburn) and to stressors associated with localized heating and cooling. More generally, the results described here facilitate rapid, non-invasive thermal measurements on broad classes of biological and non-biological soft materials.

Reliable, low-cost, fully integrated hydration sensors for monitoring and diagnosis of inflammatory skin diseases in any environment

“…As further validation, the SHS output for T versus time (t) on standard materials with known k produces the expected, qualitatively inverse relationship between T and k ( Fig. 2F) (11). SHS measurements are calibrated against the T versus t curve for water (which has known k = 0.6 W-K,  = 0.14 mm 2 /s).…”

Continuous, noninvasive wireless monitoring of flow of cerebrospinal fluid through shunts in patients with hydrocephalus

“…Soft, flexible, wireless sensors for continuous flow monitoring The basic principles of the measurement can be found elsewhere [36][37][38][39] . In the devices reported here, a miniaturized (<5 mm diameter) thermal actuator delivers small, precisely controlled thermal power (<5 mW/mm 2 ) to the surface of the skin, thereby creating an imperceptible local increase in temperature (~5 K).…”

Cohabiting Plant‐Wearable Sensor In Situ Monitors Water Transport in Plant

“…[6][7][8] New opportunities to address these problems emerge recently owing to the tremendous advances in flexible electronic technology. [9][10][11][12] This technology has led to the development of wearable or skin-attachable electronic sensors that can softly laminate onto the epidermis of a person, thus opened opportunities for the seamless and continuous assessments of the physiological status of humans, such as vital signs, [12][13][14] body kinematics, [15][16][17][18][19][20] and chemicals in sweat. [21][22][23][24] Despite the rapid development of flexible wearable sensors for the human being, the development of plant wearable sensors is significantly left behind.…”