A Review of Smart Materials in Tactile Actuators for Information Delivery

Xie, Xin; Liu, Sanwei; Yang, Chenye; Yang, Zhengyu; Liu, Tian; Xu, Juncai; Zhang, Cheng; Zhai, Xianglin

doi:10.3390/c3040038

Cited by 20 publications

(9 citation statements)

References 72 publications

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“…At lower frequencies (< 50 Hz), Meissner's corpuscles are the mechanoreceptors responsible for vibratory sensation. They reach maximum sensitivity between 20 Hz and 50 Hz [86] and play a major role in texture discrimination [87]. Due to their fast-dynamic response to a wide range of vibration frequencies, the piezoelectric elements of the ZnO NRs-based tactile sensor proposed in this study mimic the behavior of the Pacinian and Meissner afferents and can be used to develop electronic skins for robotics applications.…”

Section: Possible Sensor Design Improvementsmentioning

confidence: 99%

Seedless Hydrothermal Growth of ZnO Nanorods as a Promising Route for Flexible Tactile Sensors

et al. 2020

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Hydrothermal growth of ZnO nanorods has been widely used for the development of tactile sensors, with the aid of ZnO seed layers, favoring the growth of dense and vertically aligned nanorods. However, seed layers represent an additional fabrication step in the sensor design. In this study, a seedless hydrothermal growth of ZnO nanorods was carried out on Au-coated Si and polyimide substrates. The effects of both the Au morphology and the growth temperature on the characteristics of the nanorods were investigated, finding that smaller Au grains produced tilted rods, while larger grains provided vertical rods. Highly dense and high-aspect-ratio nanorods with hexagonal prismatic shape were obtained at 75 °C and 85 °C, while pyramid-like rods were grown when the temperature was set to 95 °C. Finite-element simulations demonstrated that prismatic rods produce higher voltage responses than the pyramid-shaped ones. A tactile sensor, with an active area of 1 cm2, was fabricated on flexible polyimide substrate and embedding the nanorods forest in a polydimethylsiloxane matrix as a separation layer between the bottom and the top Au electrodes. The prototype showed clear responses upon applied loads of 2–4 N and vibrations over frequencies in the range of 20–800 Hz.

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Section: Possible Sensor Design Improvementsmentioning

confidence: 99%

Seedless Hydrothermal Growth of ZnO Nanorods as a Promising Route for Flexible Tactile Sensors

et al. 2020

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“…[ 238,239 ] Visible and near‐infrared spectrometers have been coupled with unmanned aerial vehicles (UAVs) to monitor plant diseases, water usage, and nutrient deficiency nondestructively. [ 240 ] While these platforms can be used to interrogate plants’ physical features remotely, they often rely on the manifestation of stresses to trigger plant phenotypic changes, rendering early diagnosis of crop health difficult. [ 238,239 ]…”

Section: Novel Materials Concepts For Urban Farmingmentioning

confidence: 99%

Novel Materials for Urban Farming

Zhang

et al. 2021

Advanced Materials

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Scarcity of natural resources, shifting demographics, climate change, and increasing waste are four major challenges in the quest to feed the exploding world population. These challenges serve as the impetus to harness novel technologies to improve agriculture, productivity, and sustainability. Urban farming has several advantages over conventional farming: higher productivity, improved sustainability, and the ability to provide fresh food all year round. Novel materials are key to accelerating the evolution of urban farming – with their ability to facilitate controlled release of nutrients and pesticides, improved seed health, substrates with better water retention capability, more efficient recycling of agricultural waste, and precise plant health monitoring. Materials science enables environmental sustainability and higher harvest yields in urban farms. Here, Singapore is used as an example of a land‐scarce city where urban farming may be the solution for future food production. Potential research directions and challenges in urban farming are highlighted, and how material optimization and innovation drive the development of urban farming to meet national and global food demands is briefly discussed. This review serves as a guide for researchers and a reference for stakeholders of urban farms, policy makers, and other interested parties.

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“…Kinesthetic solutions simulate mechanical interaction by applying resistive forces to the hand/fingers using mounted exoskeletons (Choi et al 2016 ; CyberGrasp; In et al 2011 ) or stationary desktop devices e.g., Omega (omega.3) and Touch haptic device (Touch haptic device). Tactile feedback, on the other side, can be provided using various technologies to stimulate the skin such as smart materials (piezoelectric actuators, electroactive polymers, pneumatic actuators) (Xie et al 2017 ), ultrasound, pin-arrays, skin-stretch, and vibrotactile stimulation (Bermejo and Hui 2021 ; Pacchierotti et al 2017 ). Although kinesthetic solutions allow communicating modality-matched feedback (force reflected as force), a common drawback of those technologies is that they are bulky and therefore challenging to translate into a compact wearable system.…”

Section: Introductionmentioning

confidence: 99%

Encoding contact size using static and dynamic electrotactile finger stimulation: natural decoding vs. trained cues

Henrich,

Garenfeld,

Malesevic

et al. 2024

Exp Brain Res

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Electrotactile stimulation through matrix electrodes is a promising technology to restore high-resolution tactile feedback in extended reality applications. One of the fundamental tactile effects that should be simulated is the change in the size of the contact between the finger and a virtual object. The present study investigated how participants perceive the increase of stimulation area when stimulating the index finger using static or dynamic (moving) stimuli produced by activating 1 to 6 electrode pads. To assess the ability to interpret the stimulation from the natural cues (natural decoding), without any prior training, the participants were instructed to draw the size of the stimulated area and identify the size difference when comparing two consecutive stimulations. To investigate if other “non-natural” cues can improve the size estimation, the participants were asked to enumerate the number of active pads following a training protocol. The results demonstrated that participants could perceive the change in size without prior training (e.g., the estimated area correlated with the stimulated area, p < 0.001; ≥ two-pad difference recognized with > 80% success rate). However, natural decoding was also challenging, as the response area changed gradually and sometimes in complex patterns when increasing the number of active pads (e.g., four extra pads needed for the statistically significant difference). Nevertheless, by training the participants to utilize additional cues the limitations of natural perception could be compensated. After the training, the mismatch in the activated and estimated number of pads was less than one pad regardless of the stimulus size. Finally, introducing the movement of the stimulus substantially improved discrimination (e.g., 100% median success rate to recognize ≥ one-pad difference). The present study, therefore, provides insights into stimulation size perception, and practical guidelines on how to modulate pad activation to change the perceived size in static and dynamic scenarios.

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A Review of Smart Materials in Tactile Actuators for Information Delivery

Cited by 20 publications

References 72 publications

Seedless Hydrothermal Growth of ZnO Nanorods as a Promising Route for Flexible Tactile Sensors

Seedless Hydrothermal Growth of ZnO Nanorods as a Promising Route for Flexible Tactile Sensors

Novel Materials for Urban Farming

Encoding contact size using static and dynamic electrotactile finger stimulation: natural decoding vs. trained cues

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