We present a miniature haptic module based on electrorheological fluid, designed for conveying combined stiffness and vibrotactile sensations at a small scale. Haptic feedback is produced through electrorheological fluid’s controllable resistive force and varies with the actuator’s deformation. To demonstrate the proposed actuator’s feedback in realistic applications, a method for measuring the actuator’s deformation must be implemented for active control. To this end, in this study, we incorporate a sensor design based on a bend-sensitive resistive film to the ER haptic actuator. The combined actuator and sensor module was tested for its ability to simultaneously actuate and sense the actuator’s state under indentation. The results show that the bend sensor can accurately track the actuator’s displacement over its stroke. Thus, the proposed sensor may enable control of the output resistive force according to displacement, which may lead to more informed and engaging combined kinesthetic and tactile feedback.

Vibrotactile feedback is a key feature of many modern touch displays, which greatly enhances user experiences when interacting with an onscreen interface. Despite its popularity in small touch screen devices, this haptic feature is absent in most large displays due to a lack of suitable actuators for such applications. Thus, a growing need exists for haptic actuators capable of producing sufficient vibrations in large touch displays. This study proposes and evaluates a novel electrostatic resonant actuator (ERA) with a moving mass and dual electrodes for increased vibration feedback intensity. The dual-electrode ERA was fabricated along with a comparable single-electrode ERA to investigate the effect of the electrode configuration on the maximum vibration intensity. When measured directly on the mass, the maximum vibration intensity of the dual-electrode actuator increased by 73% compared to the single-electrode actuator. When mounted and measured on a mock panel, the maximum vibration intensity of the dual-electrode actuator increased by nearly 65% compared to a similarly mounted single-electrode actuator. These results show that the dual-electrode configuration can significantly increase the vibration intensity when compared to the conventional ERA. This demonstrates a promising potential for the use of the proposed actuator for generating vibrotactile feedback in large touch displays.

Vibrotactile feedback is a very desirable feature for many touchscreen applications, creating a more engaging and effective user experience. Although it is common in small electronic devices, this feedback is often absent in large touchscreen devices because it is difficult to provide vibration sensations and control the magnitude throughout the display. Because of their long shape (over 20 cm), touch bar displays are susceptible to the same challenges that other large display types face. Thus, there is a need for a vibrotactile actuation system capable of generating a freely positionable and fully controllable point of stimulation with satisfying force output at any point of a touch bar display. This study proposes a new spring boundary condition vibrotactile system as a way to provide such feedback in touch bar interfaces. A prototype system was created using two electrostatic resonant actuators and a thin, narrow aluminum beam to study the effect of different actuator excitation parameters on the beam’s response. By varying the number of actuators excited, magnitude, excitation frequency, and signal duration, a minimum vibration of 24.5 m/s² could be created in the beam, with the majority of the beam able to exceed 40 m/s². These results show that a targeted vibrotactile response at a given location in the beam can be achieved and sustained. This demonstrates a promising potential for generating a freely positionable and fully controllable point of vibrotactile stimulation at any point of a touch bar display.