Bidirectional haptic systems demand interfaces that combine sensing and actuation, enabling concurrent detection of tactile inputs and delivery of perceptually rich feedback across a broad frequency spectrum. However, most existing haptic technologies remain limited to simple tactile sensing or narrowband feedback, struggling to resolve continuous motions and simultaneous sensory cues required for naturalistic human-machine interaction (HMI). These limitations fundamentally constrain the fidelity and expressiveness of tactile communication, preventing current human-machine interfaces from reproducing the broadband of sensations perceived by human skin. Here, we present a large-area bidirectional human-machine interface (HMI) that utilizes a unified haptic dual-resonant actuator (UHDRA) capable of simultaneously implementing electrostatic-based multimodal tactile sensing and actuation. The system provides spatially uniform tactile stimulation over a broad frequency range of 20-250 Hz while simultaneously enabling real-time detection without interference from actuator-induced vibration. Leveraging the actuator's intrinsic structural stiffness, the interface maintains stable vibration amplitudes into the gentle-touch regime (≈2 N) while selectively modulating frequency, allowing clear discrimination of diverse tactile stimuli without perceptual discontinuity. Building on this decoupled bidirectional interaction capability, the proposed approach offers transformative potential for next-generation applications such as bidirectional telerobotic and augmented interactions.
Son et al. (Tue,) studied this question.