• Collaboration results with KRISS.

Pneumatic and hydraulic skin-contact haptic devices rely on external pumps, tubing, and valves, limiting their miniaturization and array scalability. Electroosmotic (EO) pump-based actuators mitigate this but remain limited to point-contact, single-cell operation, and delivering vibrotactile stimuli via positive pressure is difficult to localize without an added contact tip. This work proposes a large-area wearable tactile patch in which a single EO actuator, driven solely in negative-pressure mode, delivers both static and vibrotactile stimuli—matched to skin mechanoreceptor bands—without any additional contact structure. Under negative pressure the membrane deforms inward, drawing in the skin: sustained actuation yields a well-localized static stimulus, while periodic actuation yields vibrotactile feedback. Demonstration feedback indicated improved localization over positive-pressure actuation. Polarity-reversal bidirectional driving and sequential multi-cell array actuation, already established in this platform, were also demonstrated, showing that negative-pressure EO actuation extends tactile patches toward miniaturized, array-scalable wearable interfaces.

• Collaboration results with IMAGIS Corp. and Miami Univ.

Generating haptic sensations in large touch displays is highly desirable, yet producing them for such application is challenging with conventional haptic actuators used in hand-held devices. This study proposes an electrostatic actuator utilizing frequency beating phenomenon with the goals of generating haptic sensations for large touch sensitive displays (TSDs). Unlike typical electrostatic actuators, the proposed haptic actuator incorporates two high-volt electrodes and a spring supported disk (moveable grounded mass) to enhance the intensity and pattern of haptic sensations. After fabricating a proof-of-concept prototype, its performance was experimentally evaluated by varying the beat frequency and the carrier frequency. Using mock-up LCD panels, a feasibility of the proposed actuator was evaluated for generating meaningful haptic sensations in large TSDs. Testing results show that the prototype generated a variety of unique vibration patterns at varying intensities based on combinations of the two input voltage signals. The results further show that the proposed actuator can produce sufficiently strong vibrotactile feedbacks in mock-up panels, indicating that the proposed electrostatic actuators can be a viable option for providing haptic sensations in large TSDs. 

• Collaboration results with KRISS and KOREATECH

Although the output force per unit cell of electroactive polymer-based actuators is much lower than that of VCM, it is a suitable method for creating a flexible and highly integrated tactile display array. We are researching technology to produce electroactive polymer actuator arrays by compressing polymers at high density.