DragTapVib: An On-Skin Electromagnetic Drag, Tap, and Vibration Actuator for Wearable Computing

Abstract

Figure 1: (a). Structure of DragTapVib; (b). DragTapVib is a flexible and wearable actuator that renders three haptic stimuli; (c) and (d). DragTapVib can be worn on different body locations.

Multimodal 5‐DOF Stretchable Electromagnetic Actuators toward Haptic Information Delivery

“…Since our device requires a strong remnant magnetic field to interact with the external magnetic field and to form the soft magnet, we chose a hard magnetic material Neodymium Iron Boron (NdFeB) as the magnetic fillers for the soft magnet. [11,[50][51][52][53] For the matrix material, the material should be able to accommodate a high loading of NdFeB while retaining softness, which is vital for the comfortable interactions of the soft magnet with the skin. Among commonly used materials (Figure S9a, Supporting Information), Ecoflex0030 could not accommodate a high NdFeB concentration and the NdFeB/Ecoflex composite became friable at a high loading of NdFeB (8 : 1 in weight ratio).…”

“…For instance, Pacinian corpuscles primarily respond to rapid vibrations, Merkel cells are sensitive to pressure, and Ruffini endings are in response to skin stretch. [8][9][10][11] Conventional haptic devices often employ a single actuation mode, with vibration being the most commonly used stimuli. While vibration has been investigated for delivering haptic information regarding surface roughness through the application of different frequencies, [12] vibratory actuators are ineffective in conveying detailed information about shape and surface structure.…”

“…[13][14][15][16] To address the limitations of the conventional actuators and provide users with rich tactile sensations, tactile interactions in rotational shear mode have been explored, where the rotational movement of a tactor is employed to stimulate cutaneous receptors. [10,11,14,[17][18][19] Pneumatic/hydraulic actuators and servo motors have been widely explored to exert a rotational shear force. [20][21][22] Rotation shear force could generate haptic sensations that carry angular information from 3D solid surfaces, such as the edge angle and corner angle of an object.…”

“…For instance, a haptic device based on electromagnetic actuation achieved both haptic sensations, but the haptic interactions are limited to 2‐DOF. [ 11 ] Recent research efforts have been devoted to exploring a 5‐DoF actuator using shape memory alloys (SMA). [ 29 ] However, the SMA‐based actuation mechanism faces challenges in terms of response time and efficiency due to the prolonged heating/cooling time.…”

“…Previous user studies have revealed that devices without stretchability have led to poor efficiency in haptic interactions as well as unsatisfied user experiences. [ 11,24,39 ] Skin‐like stretchability and softness are essential to minimize the influence on the user's intuitive actions, improve the mechanical robustness of the device during daily skin deformations, and more importantly, ensure intimate skin contact for precise delivery of mechanical stimuli.…”