Virtual reality and augmented reality (VR/AR) are evolving. The market demands and innovation efforts call for a shift in the key VR/AR technologies and engaging people virtually. Tele‐haptics with multimodal and bilateral interactions are emerging as the future of the VR/AR industry. By transmitting and receiving haptic sensations wirelessly, tele‐haptics allow human‐to‐human interactions beyond the traditional VR/AR interactions. The core technologies for tele‐haptics include multimodal tactile sensing and feedback based on highly advanced sensors and actuators. Recent developments of haptic innovations based on active materials show that active materials can significantly contribute to addressing the needs and challenges for the current and future VR/AR technologies. Thus, this paper intends to review the current status and opportunities of active material‐based haptic technology with a focus on VR/AR applications. It first provides an overview of the current VR/AR applications of active materials for haptic sensing and actuation. It then highlights the state‐of‐the‐art haptic interfaces that are relevant to the materials with an aim to provide perspectives on the role of active materials and their potential integration in haptic devices. This paper concludes with the perspective and outlook of immersive multimodal tele‐haptic interaction technologies.

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 seamless integration of rigid/flexible electronic components into stretchable substrates is imperative for the realization of reliable stretchable electronics. However, the transition from flexible-to-stretchable substrates presents inherent challenges in interfacial behavior, predominantly arising from disparities in elastic moduli, thereby rendering their integration arduous for practical deployment. Here, we introduce a bioinspired interface-engineered flexible island (BIEFI), which effectively facilitates the creation of highly stretchable electronics by optimizing the interface with flexible mechanical interlocking mechanisms, resilient to physical deformations. Various electronic components, such as light-emitting diodes (LEDs) and solar cells, are affixed onto the flexible island, showcasing its versatility as a robust platform for rigid components while ensuring the entire substrate maintains high stretchability. Additionally, a smart workout monitoring system is demonstrated by integrating a resistance band with a flexible-to-stretchable platform. This approach seamlessly integrates a wide range of rigid, flexible, and stretchable components, ensuring durability under diverse physical deformations.

This paper reports on an improved piezoelectric microspeaker with a high sound pressure level of 90 dB, a total harmonic distortion of less than 15%, and coherence higher than 0.9. The fabricated Pb(Zr,Ti)O₃ (PZT) microspeakers have a thickness of only 1 mm including the speaker frame and an active area of 18 mm×20 mm. To achieve higher sound pressure and lower distortion, the PZT piezoelectric microspeaker has a well-designed speaker frame and a piezoelectric diaphragm consisting of a tilted PZT membrane and silicone buffer layer. From the simulation and measurement results, we confirmed that the silicon buffer layer can lower the first resonant frequency, which enhances the microspeaker's sound pressure at a low frequency range and can also reduce useless distortion generated by the harmonics. The fabricated PZT piezoelectric microspeakers are implemented on a multichannel speaker array system for personal acoustical space generation. The output sound pressure at a 30 cm distance away from the center of the speaker line array is 15 dB higher than the sound pressure at the neighboring region 30 degrees from the vertical axis.

To accurately probe the tactile information on soft skin, it is critical for the pressure sensing array to be free of noise and inter-taxel crosstalk, irrespective of the measurement condition. However, on dynamically moving and soft surfaces, which are common conditions for on-skin and robotic applications, obtaining precise measurement without compromising the sensing performance is a significant challenge due to mechanical coupling between the sensors and with the moving surface. In this work, multi-level architectural design of micro-pyramids and trapezoid-shaped mechanical barrier array was implemented to enable accurate spatiotemporal tactile sensing on soft surfaces under dynamic deformations. Trade-off relationship between limit of detection and bending insensitivity was discovered, which was overcome by employing micropores in barrier structures. Finally, in-situ pressure mapping on dynamically moving soft surfaces without signal distortion is demonstrated while human skin and/or soft robots are performing complicated tasks such as reading Braille and handling the artificial organs.