Deformable Ionic Polymer Artificial Mechanotransducer with an Interpenetrating Nanofibrillar Network.

We demonstrate an ionic polymer artificial mechanotransducer (i-PAM) capable of simultaneously yielding an efficient wide bandwidth and a blocking force to maximize human tactile recognition in soft tactile feedback. The unique methodology in the i-PAM relies on an ionic interpenetrating nanofibrillar network that is formed at the interface of (i) an ionic thermoplastic polyurethane nanofibrillar matrix with an ionic liquid of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM]+[TFSI]-) and (ii) ionic poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) conducting polymer electrodes with dimethyl sulfoxide and [EMIM]+[TFSI]- as additives. The i-PAM-based actuator with the ionic PEDOT:PSS exhibits a stable operation up to 200 Hz at low voltage as well as a blocking force of 0.4 mN, which can be potentially adapted to soft tactile feedback. Furthermore, on the basis of this fast i-PAM, we realized alphabet tactile rendering by using a 3 × 3 i-PAM array stimulated by a dc input of 2 V. We believe that our proposed approach can provide a rational guide to the human-machine soft haptic interface.

Electrically Controllable Molecularization of Terahertz Meta-Atoms.

Active control of metamaterial properties is critical for advanced terahertz (THz) applications. However, the tunability of THz properties, such as the resonance frequency and phase of the wave, remains challenging. Here, a new device design is provided for extensively tuning the resonance properties of THz metamaterials. Unlike previous approaches, the design is intended to control the electrical interconnections between the metallic unit structures of metamaterials. This strategy is referred to as the molecularization of the meta-atoms and is accomplished by placing graphene bridges between the metallic unit structures whose conductivity is modulated by an electrolyte gating. Because of the scalable nature of the molecularization, the resonance frequency of the terahertz metamaterials can be tuned as a function of the number of meta-atoms constituting a unit metamolecule. At the same time, the voltage-controlled molecularization allows delicate control over the phase shift of the transmitted THz, without changing the high transmission of the materials significantly.