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Objective Interface pressure, the sine qua non for compression therapy, is rarely measured in clinical practice and scientific research. The goal of this study aimed to compare and examine the accuracy between a commercially available piezoresistive sensor and PicoPress® (Microlab, Padua, Italy) using the cylinder cuff model to measure in-vitro interface pressure. Method Ten piezoresistive sensors were calibrated using the National Institute of Standard and Technology certified manometer, and compared to PicoPress® using cylinder cuff model from 20 to 120 mmHg. Two statistical analyses were performed: (a) two-sample t-test to compare the front to back surface of the piezoresistive sensors using mean pressure value and (b) one-sample paired t-test to compare the front and back surface of the piezoresistive sensors to PicoPress® and true pressure using mean pressure value. Result There was no difference in interface pressure measurement between the front and back surface of the piezoresistive sensors (P > 0.05). Using mean pressure value, there was no significant difference between the front surface, back surface of the piezoresistive sensors, and PicoPress® (P > 0.05). Standard deviation was larger for the piezoresistive sensors than PicoPress® at any given pressure and this difference was more pronounced in the higher pressure range. Conclusion Piezoresistive sensor may represent a viable alternative to PicoPress® in interface pressure measurement.

A flexible, transparent iontronic film is introduced as a thin-film capacitive sensing material for emerging wearable and health-monitoring applications. Utilizing the capacitive interface at the ionic-electronic contact, the iontronic film sensor offers a large unit-area capacitance (of 5.4 μF cm(-2) ) and an ultrahigh sensitivity (of 3.1 nF kPa(-1) ), which is a thousand times greater than that of traditional solid-state counterparts., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

An iontronic microdroplet array (IMA) device, using an ultra-large interfacial capacitance at the highly elastic droplet-electrode contact, has been proposed for flexible tactile sensing applications. The transparent IMA sensors consist of an array of nanoliter droplets sandwiched between two polymeric membranes with patterned transparent electrodes, forming the electrical double layers with remarkable unit-area capacitance. Under external loading, the membrane deformation results in the circumferential expansion at the highly elastic droplet-electrode contact, which offers a completely new capacitive sensing scheme with a dramatic increase in sensitivity. Under the simple device architecture, the IMA has achieved device sensitivity of 0.43 nF kPa(-1) and a minimal detectable pressure of 33 Pa, the highest reported values for its dimension. In addition, the hysteresis of the droplet deformation has been reduced by introducing a layer of hydrophobic coating to the conductive electrode surface, ensuring a fast mechanical response (on the order of several milliseconds). To demonstrate the utility of the transparent flexible IMA sensor, it has been successfully mounted onto a fingertip setting to map different surface topologies and embedded into a wristband to resolve dynamic pressure waves throughout cardiovascular cycles.