Search for: All records

Haptic devices enable communication via touch, augmenting visual and auditory displays, or by offering alternative channels of communication when vision and hearing are unavailable. Because of the different types of haptic stimuli that are perceivable by users — vibration, skin stretch, pressure and temperature, among others — devices can be designed to communicate complex information by delivering multiple types of haptic stimuli simultaneously. These multi-sensory haptic devices are often designed to be wearable and have been developed for use in a wide variety of applications, including communication, entertainment and rehabilitation. Multi-sensory haptic devices present unique challenges to designers because human perceptual acuity can vary widely depending on the wearable location on the body and/or the heterogeneity in human perceptual performance, particularly when multiple cues are presented simultaneously. Additionally, packaging haptic systems in a wearable form factor presents its own engineering challenges such as cue masking, device mounting and actuator capabilities, among others. Thus, in this Review, we discuss the state-of-the-art and specific obstacles present in the field to produce multi-sensory devices that enhance the human capacity for haptic interaction and information transmission. 

Thin, flexible sheets can be patterned and bonded to form internal fluidic networks, which enable actuation, sensing, and control, but failure of these sheet-based systems—and how to take advantage of this failure—remains relatively unexplored. Here, we examine this concept using heat-sealable textiles as a material platform. We determine the effects of geometry and material processing on bond strength and burst pressure; these findings can ensure a sheet-based fluidic system is sufficiently robust for a given use case. Building on this framework, we introduce a fuse-like component into which failure is deliberately programmed. In addition to limiting damage in the case of overpressurization, we leverage this programmed failure to enable distinct capabilities including (1) the binary selection of operating modes and (2) the sequencing of a series of tasks with a single pressure input. These findings will facilitate the development of more intelligent sheet-based fluidic systems. 

Silicone elastomers exhibit extraordinary compliance, positioning them as a material of choice for soft robots and devices. To accelerate curing times of platinum-catalyzed silicone elastomers, researchers have employed elevated temperatures; however, knowledge of the requisite duration for curing at a given temperature has remained limited to specific elastomers and has relied primarily on empirical trends. This work presents an analytical model based on an Arrhenius framework coupled with data from thermo-rheological experiments to provide guidelines for suitable curing conditions for commercially available addition-cured platinum-catalyzed silicone elastomers. The curing reaction exhibits self-similarity upon normalizing to a dimensionless reaction coordinate, allowing quantification of the extent of curing under arbitrary time-varying thermal conditions. Mechanical testing revealed no significant changes in properties or performance as a result of thermally accelerated curing. With this framework, higher throughput of elastomeric components can be achieved, and the design space for elastomer-based manufacturing can be developed beyond conventional casting. 

Vibration is a widely used mode of haptic communication, as vibrotactile cues provide salient haptic notifications to users and are easily integrated into wearable or handheld devices. Fluidic textile-based devices offer an appealing platform for the incorporation of vibrotactile haptic feedback, as they can be integrated into clothing and other conforming and compliant wearables. Fluidically driven vibrotactile feedback has primarily relied on valves to regulate actuating frequencies in wearable devices. The mechanical bandwidth of such valves limits the range of frequencies that can be achieved, particularly in attempting to reach the higher frequencies realized with electromechanical vibration actuators ( > 100 Hz). In this paper, we introduce a soft vibrotactile wearable device, constructed entirely of textiles and capable of rendering vibration frequencies between 183 and 233 Hz with amplitudes ranging from 23 to 114 g . We describe our methods of design and fabrication and the mechanism of vibration, which is realized by controlling inlet pressure and harnessing a mechanofluidic instability. Our design allows for controllable vibrotactile feedback that is comparable in frequency and greater in amplitude relative to state-of-the-art electromechanical actuators while offering the compliance and conformity of fully soft wearable devices. 

Vibration is ubiquitous as a mode of haptic communication, and is used widely in handheld devices to convey events and notifications. The miniaturization of electromechanical actuators that are used to generate these vibrations has enabled designers to embed such actuators in wearable devices, conveying vibration at the wrist and other locations on the body. However, the rigid housings of these actuators mean that such wearables cannot be fully soft and compliant at the interface with the user. Fluidic textile-based wearables offer an alternative mechanism for haptic feedback in a fabric-like form factor. To our knowledge, fluidically driven vibrotactile feedback has not been demonstrated in a wearable device without the use of valves, which can only enable low-frequency vibration cues and detract from wearability due to their rigid structure. We introduce a soft vibrotactile wearable, made of textile and elastomer, capable of rendering high-frequency vibration. We describe our design and fabrication methods and the mechanism of vibration, which is realized by controlling inlet pressure and harnessing a mechanical hysteresis. We demonstrate that the frequency and amplitude of vibration produced by our device can be varied based on changes in the input pressure, with 0.3 to 1.4 bar producing vibrations that range between 160 and 260 Hz at 13 to 38 g, the acceleration due to gravity. Our design allows for controllable vibrotactile feedback that is comparable in frequency and outperforms in amplitude relative to electromechanical actuators, yet has the compliance and conformity of fully soft wearable devices. 

Haptic feedback offers a useful mode of communication in visually or auditorily noisy environments. The adoption of haptic devices in our everyday lives, however, remains limited, motivating research on haptic wearables constructed from materials that enable comfortable and lightweight form factors. Textiles, a material class fitting these needs and already ubiquitous in clothing, have begun to be used in haptics, but reliance on arrays of electromechanical controllers detracts from the benefits that textiles offer. Here, we mitigate the requirement for bulky hardware by developing a class of wearable haptic textiles capable of delivering high-resolution information on the basis of embedded fluidic programming. The designs of these haptic textiles enable tailorable amplitudinal, spatial, and temporal control. Combining these capabilities, we demonstrate wearables that deliver spatiotemporal cues in four directions with an average user accuracy of 87%. Subsequent demonstrations of washability, repairability, and utility for navigational tasks exemplify the capabilities of our approach. 

In 2020, cardiovascular diseases resulted in 25% of unnatural deaths in the United States. Treatment with long-term administration of medication can adversely affect other organs, and surgeries such as coronary artery grafts are risky. Meanwhile, sequential compression therapy (SCT) offers a low-risk alternative, but is currently expensive and unwieldy, and often requires the patient to be immobilized during administration. Here, we present a low-cost wearable device to administer SCT, constructed using a stacked lamination fabrication approach. Expanding on concepts from the field of soft robotics, textile sheets are thermally bonded to form pneumatic actuators, which are controlled by an inconspicuous and tetherless electronic onboard supply of pressurized air. Our open-source, low-profile, and lightweight (140 g) device costs $62, less than one-third the cost the least expensive alternative and one-half the weight of lightest alternative approved by the US Food and Drug Administration (FDA), presenting the opportunity to more effectively provide SCT to socioeconomically disadvantaged individuals. Furthermore, our textile-stacking method, inspired by conventional fabrication methods from the apparel industry, along with the lightweight fabrics used, allows the device to be worn more comfortably than other SCT devices. By reducing physical and financial encumbrances, the device presented in this work may better enable patients to treat cardiovascular diseases and aid in recovery from cardiac surgeries.