Touchable Gustation via a Hoffmeister Gel Iontronic Sensor.

A particular sense, touchable gustation, was achieved. We proposed a chemical-mechanical interface strategy with an iontronic sensor device. A conductive hydrogel, amino trimethylene phosphonic acid (ATMP) assisted poly(vinyl alcohol) (PVA), was employed as the dielectric layer of the gel iontronic sensor. The Hofmeister effect of the ATMP-PVA hydrogel was well investigated to establish the quantitative description of the gel elasticity modulus to chemical cosolvents. The mechanical properties of hydrogels can be transduced extensively and reversibly by regulating the aggregation state of polymer chains with hydrated ions or cosolvents. Scanning electron microscopy (SEM) images of ATMP-PVA hydrogel microstructures stained with different soaked cosolvents present different networks. The information on different chemical components will be stored in the ATMP-PVA gels. The flexible gel iontronic sensor with a hierarchical pyramid structure performed high linear sensitivity of 3224.2 kPa and wide pressure response in the range of 0-100 kPa. The finite element analysis proved the pressure distribution at the gel interface of the gel iontronic sensor and the capacitation-stress response relation. Various cations, anions, amino acids, and saccharides can be discriminated, classified, and quantified with the gel iontronic sensor. The Hofmeister effect regulated chemical-mechanical interface performs the response and conversion of biological/chemical signals into electrical output in real time. The particular function to tactile with gustation percept will contribute promising applications in the human-machine interaction, humanoid robot, clinic treatment, or athletic training optimization.