Realizing highly immersive tactile interactions requires a skin-integrated, untethered, high-definition tactile transducer devices that can record and generate tactile stimuli. However, the rigid and bulky form factor, and insufficient resolution of existing actuators are hindering the reproduction of sophisticated tactile sensations and immersive user experiences. Here, we demonstrate an ultra-flexible tactile interface with high spatial resolution of 1.8 mm for telehaptic communication on human skin. Dual mechanism sensors and sub-mm scale piezoceramic actuators are designed to record and generate the static and dynamic pressures in a wide frequency range (1 Hz to 1 kHz). Moreover, actuators are integrated on ultra-flexible substrate with chessboard pattern to minimize stress during mechanical deformations. Finally, remote transmissions of various tactile stimuli, such as shapes, textures, and vibration patterns were demonstrated by the telehaptic system with low latency (<1.55 ms) and high fidelity as proven by the short-time Fourier-transform analysis.

The vibrational characteristics of 3 types of the acoustic diaphragms are investigated to enhance the output acoustic performance of the piezoelectric ceramic speaker in a low-frequency range. In other to achieve both a higher output sound pressure level and wider frequency range of the piezoelectric speaker, we have proposed a rubber/resin bi-layer acoustic diaphragm. The theoretical square-root dependence of the fundamental resonant frequency on the thickness and Young's modulus of the acoustic diaphragm was verified by finite-element analysis simulation and laser scanning vibrometer measurement. The simulated resonant frequencies for each diaphragm correspond well to the measured results. From the simulated and measured resonant frequency results, it is found that the fundamental resonant frequency of the piezoelectric ceramic speaker can be designed by adjusting the thickness ratio of the rubber/resin bi-layer acoustic diaphragm. Compared with a commercial piezoelectric speaker, the fabricated piezoelectric ceramic speaker with the rubber/resin bi-layer diaphragm has at least 10 dB higher sound pressures in the low-frequency range of less than 1 kHz.

This paper presents a novel, highly sensitive condenser microphone with a flexure hinge diaphragm. We used the finiteelement analysis (FEA) to evaluate the mechanical and acoustic performance of the condenser microphone with a hinge diaphragm. And we fabricated the miniature condenser microphones with area of 1.5 mm x 1.5 mm. From the simulation and measurement results, we confirmed that the maximum displacements at the center of flexure hinge diaphragms are several hundred times, compared with flat diaphragms. Moreover, the miniature microphones have obtained -3 dB bandwidth of nearly 20 kHz by proper design of the flexure hinge diaphragms.