Full Dynamic-Range Pressure Sensor Matrix Based on Optical and Electrical Dual-Mode Sensing.
TL;DR: A pressure-sensor matrix with full dynamic range can accurately detect and spatially map pressure profiles and represents a major step toward digital imaging.
Abstract: A pressure-sensor matrix (PSM) with full dynamic range can accurately detect and spatially map pressure profiles. A 100 × 100 large-scale PSM gives both electrical and optical signals by itself without applying an external power source. The device represents a major step toward digital imaging, and the visible display of the pressure distribution covers a large dynamic range.
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TL;DR: The versatile and scalable Ti3C2Tx MXene/CNT strain sensors provide a promising route to future wearable artificial intelligence with comprehensive tracking ability of real-time and in situ physiological signals for health and sporting applications.
Abstract: It remains challenging to fabricate strain-sensing materials and exquisite geometric constructions for integrating extraordinary sensitivity, low strain detectability, high stretchability, tunable sensing range, and thin device dimensions into a single type of strain sensor. A percolation network based on Ti3C2Tx MXene/carbon nanotube (CNT) composites was rationally designed and fabricated into versatile strain sensors. This weaving architecture with excellent electric properties combined the sensitive two-dimensional (2D) Ti3C2Tx MXene nanostacks with conductive and stretchable one-dimensional (1D) CNT crossing. The resulting strain sensor can be used to detect both tiny and large deformations with an ultralow detection limit of 0.1% strain, high stretchability (up to 130%), high sensitivity (gauge factor up to 772.6), tunable sensing range (30% to 130% strain), thin device dimensions ( 5000 cycles). The versatile and scalable Ti3C2Tx MXene/CNT strain sens...
605 citations
TL;DR: The RDS microstructure provides an alternative strategy to improve the performance of pressure sensors and extend their potential applications in monitoring human activities through the combination of an abrasive paper template and reduced graphene oxide.
Abstract: Recently, wearable pressure sensors have attracted tremendous attention because of their potential applications in monitoring physiological signals for human healthcare. Sensitivity and linearity are the two most essential parameters for pressure sensors. Although various designed micro/nanostructure morphologies have been introduced, the trade-off between sensitivity and linearity has not been well balanced. Human skin, which contains force receptors in a reticular layer, has a high sensitivity even for large external stimuli. Herein, inspired by the skin epidermis with high-performance force sensing, we have proposed a special surface morphology with spinosum microstructure of random distribution via the combination of an abrasive paper template and reduced graphene oxide. The sensitivity of the graphene pressure sensor with random distribution spinosum (RDS) microstructure is as high as 25.1 kPa–1 in a wide linearity range of 0–2.6 kPa. Our pressure sensor exhibits superior comprehensive properties com...
498 citations
TL;DR: A self-powered piezoelectric pulse sensor is demonstrated to enable in vivo measurement of radial/carotid pulse signals in near-surface arteries and wireless transmission of detected arterial pressure signals to a smart phone demonstrates the possibility of self- powered and real-time pulse monitoring system.
Abstract: Continuous monitoring of an arterial pulse using a pressure sensor attached on the epidermis is an important technology for detecting the early onset of cardiovascular disease and assessing personal health status. Conventional pulse sensors have the capability of detecting human biosignals, but have significant drawbacks of power consumption issues that limit sustainable operation of wearable medical devices. Here, a self-powered piezoelectric pulse sensor is demonstrated to enable in vivo measurement of radial/carotid pulse signals in near-surface arteries. The inorganic piezoelectric sensor on an ultrathin plastic achieves conformal contact with the complex texture of the rugged skin, which allows to respond to the tiny pulse changes arising on the surface of epidermis. Experimental studies provide characteristics of the sensor with a sensitivity (≈0.018 kPa-1 ), response time (≈60 ms), and good mechanical stability. Wireless transmission of detected arterial pressure signals to a smart phone demonstrates the possibility of self-powered and real-time pulse monitoring system.
399 citations
TL;DR: A self-powered, highly stretchable, and transparent triboelectric tactile sensor with patterned Ag-nanofiber electrodes for detecting and spatially mapping trajectory profiles is reported, which has widespread potential in tactile sensing and touchpad technology applications.
Abstract: Recently, the quest for new highly stretchable transparent tactile sensors with large-scale integration and rapid response time continues to be a great impetus to research efforts to expand the promising applications in human-machine interactions, artificial electronic skins, and smart wearable equipment. Here, a self-powered, highly stretchable, and transparent triboelectric tactile sensor with patterned Ag-nanofiber electrodes for detecting and spatially mapping trajectory profiles is reported. The Ag-nanofiber electrodes demonstrate high transparency (>70%), low sheet resistance (1.68-11.1 Ω □-1 ), excellent stretchability, and stability (>100% strain). Based on the electrode patterning and device design, an 8 × 8 triboelectric sensor matrix is fabricated, which works well under high strain owing to the effect of the electrostatic induction. Using cross-locating technology, the device can execute more rapid tactile mapping, with a response time of 70 ms. In addition, the object being detected can be made from any commonly used materials or can even be human hands, indicating that this device has widespread potential in tactile sensing and touchpad technology applications.
314 citations
TL;DR: A flexible ferro electric sensor with ultrahigh pressure sensitivity and linear response over an exceptionally broad pressure range based on the material and structural design of ferroelectric composites with a multilayer interlocked microdome geometry is demonstrated.
Abstract: Flexible pressure sensors with a high sensitivity over a broad linear range can simplify wearable sensing systems without additional signal processing for the linear output, enabling device miniaturization and low power consumption. Here, we demonstrate a flexible ferroelectric sensor with ultrahigh pressure sensitivity and linear response over an exceptionally broad pressure range based on the material and structural design of ferroelectric composites with a multilayer interlocked microdome geometry. Due to the stress concentration between interlocked microdome arrays and increased contact area in the multilayer design, the flexible ferroelectric sensors could perceive static/dynamic pressure with high sensitivity (47.7 kPa–1, 1.3 Pa minimum detection). In addition, efficient stress distribution between stacked multilayers enables linear sensing over exceptionally broad pressure range (0.0013–353 kPa) with fast response time (20 ms) and high reliability over 5000 repetitive cycles even at an extremely hi...
310 citations
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TL;DR: In this article, the authors demonstrate a simple, low cost and effective approach of using the charging process in friction to convert mechanical energy into electric power for driving small electronics, which is fabricated by stacking two polymer sheets made of materials having distinctly different triboelectric characteristics, with metal films deposited on the top and bottom of the assembled structure.
4,069 citations
TL;DR: This work bridges the technological gap between signal transduction, conditioning, processing and wireless transmission in wearable biosensors by merging plastic-based sensors that interface with the skin with silicon integrated circuits consolidated on a flexible circuit board for complex signal processing.
Abstract: Wearable sensor technologies are essential to the realization of personalized medicine through continuously monitoring an individual's state of health. Sampling human sweat, which is rich in physiological information, could enable non-invasive monitoring. Previously reported sweat-based and other non-invasive biosensors either can only monitor a single analyte at a time or lack on-site signal processing circuitry and sensor calibration mechanisms for accurate analysis of the physiological state. Given the complexity of sweat secretion, simultaneous and multiplexed screening of target biomarkers is critical and requires full system integration to ensure the accuracy of measurements. Here we present a mechanically flexible and fully integrated (that is, no external analysis is needed) sensor array for multiplexed in situ perspiration analysis, which simultaneously and selectively measures sweat metabolites (such as glucose and lactate) and electrolytes (such as sodium and potassium ions), as well as the skin temperature (to calibrate the response of the sensors). Our work bridges the technological gap between signal transduction, conditioning (amplification and filtering), processing and wireless transmission in wearable biosensors by merging plastic-based sensors that interface with the skin with silicon integrated circuits consolidated on a flexible circuit board for complex signal processing. This application could not have been realized using either of these technologies alone owing to their respective inherent limitations. The wearable system is used to measure the detailed sweat profile of human subjects engaged in prolonged indoor and outdoor physical activities, and to make a real-time assessment of the physiological state of the subjects. This platform enables a wide range of personalized diagnostic and physiological monitoring applications.
3,235 citations
TL;DR: Transparent, conducting spray-deposited films of single-walled carbon nanotubes are reported that can be rendered stretchable by applying strain along each axis, and then releasing this strain.
Abstract: Transparent films of carbon nanotubes can accommodate strains of up to 150% and demonstrate conductivities as high as 2,200 S cm−1 in the stretched state.
2,847 citations
TL;DR: In this paper, the authors present a platform that makes electronics both virtually unbreakable and imperceptible on polyimide polysilicon elastomers, which can be operated at high temperatures and in aqueous environments.
Abstract: Electronic devices have advanced from their heavy, bulky origins to become smart, mobile appliances. Nevertheless, they remain rigid, which precludes their intimate integration into everyday life. Flexible, textile and stretchable electronics are emerging research areas and may yield mainstream technologies. Rollable and unbreakable backplanes with amorphous silicon field-effect transistors on steel substrates only 3 μm thick have been demonstrated. On polymer substrates, bending radii of 0.1 mm have been achieved in flexible electronic devices. Concurrently, the need for compliant electronics that can not only be flexed but also conform to three-dimensional shapes has emerged. Approaches include the transfer of ultrathin polyimide layers encapsulating silicon CMOS circuits onto pre-stretched elastomers, the use of conductive elastomers integrated with organic field-effect transistors (OFETs) on polyimide islands, and fabrication of OFETs and gold interconnects on elastic substrates to realize pressure, temperature and optical sensors. Here we present a platform that makes electronics both virtually unbreakable and imperceptible. Fabricated directly on ultrathin (1 μm) polymer foils, our electronic circuits are light (3 g m(-2)) and ultraflexible and conform to their ambient, dynamic environment. Organic transistors with an ultra-dense oxide gate dielectric a few nanometres thick formed at room temperature enable sophisticated large-area electronic foils with unprecedented mechanical and environmental stability: they withstand repeated bending to radii of 5 μm and less, can be crumpled like paper, accommodate stretching up to 230% on prestrained elastomers, and can be operated at high temperatures and in aqueous environments. Because manufacturing costs of organic electronics are potentially low, imperceptible electronic foils may be as common in the future as plastic wrap is today. Applications include matrix-addressed tactile sensor foils for health care and monitoring, thin-film heaters, temperature and infrared sensors, displays, and organic solar cells.
2,062 citations
TL;DR: Electronic networks comprised of flexible, stretchable, and robust devices that are compatible with large-area implementation and integrated with multiple functionalities is a testament to the progress in developing an electronic skin akin to human skin.
Abstract: Human skin is a remarkable organ. It consists of an integrated, stretchable network of sensors that relay information about tactile and thermal stimuli to the brain, allowing us to maneuver within our environment safely and effectively. Interest in large-area networks of electronic devices inspired by human skin is motivated by the promise of creating autonomous intelligent robots and biomimetic prosthetics, among other applications. The development of electronic networks comprised of flexible, stretchable, and robust devices that are compatible with large-area implementation and integrated with multiple functionalities is a testament to the progress in developing an electronic skin (e-skin) akin to human skin. E-skins are already capable of providing augmented performance over their organic counterpart, both in superior spatial resolution and thermal sensitivity. They could be further improved through the incorporation of additional functionalities (e.g., chemical and biological sensing) and desired properties (e.g., biodegradability and self-powering). Continued rapid progress in this area is promising for the development of a fully integrated e-skin in the near future.
1,950 citations