Abstract
Advancements of virtual reality technology pave the way for developing wearable devices to enable somatosensory sensation, which can bring more comprehensive perception and feedback in ...the metaverse-based virtual society. Here, we propose augmented tactile-perception and haptic-feedback rings with multimodal sensing and feedback capabilities. This highly integrated ring consists of triboelectric and pyroelectric sensors for tactile and temperature perception, and vibrators and nichrome heaters for vibro- and thermo-haptic feedback. All these components integrated on the ring can be directly driven by a custom wireless platform of low power consumption for wearable/portable scenarios. With voltage integration processing, high-resolution continuous finger motion tracking is achieved via the triboelectric tactile sensor, which also contributes to superior performance in gesture/object recognition with artificial intelligence analysis. By fusing the multimodal sensing and feedback functions, an interactive metaverse platform with cross-space perception capability is successfully achieved, giving people a face-to-face like immersive virtual social experience.
As a natural monitor of health conditions for human beings, volatile organic compounds (VOCs) act as significant biomarkers for healthcare monitoring and early stage diagnosis of diseases. Most ...existing VOC sensors use semiconductors, optics, and electrochemistry, which are only capable of measuring the total concentration of VOCs with slow response, resulting in the lack of selectivity and low efficiency for VOC detection. Infrared (IR) spectroscopy technology provides an effective solution to detect chemical structures of VOC molecules by absorption fingerprints induced by the signature vibration of chemical stretches. However, traditional IR spectroscopy for VOC detection is limited by the weak light-matter interaction, resulting in large optical paths. Leveraging the ultrahigh electric field induced by plasma, the vibration of the molecules is enhanced to improve the light-matter interaction. Herein, we report a plasma-enhanced IR absorption spectroscopy with advantages of fast response, accurate quantization, and good selectivity. An order of ∼kV voltage was achieved from the multiswitched manipulation of the triboelectric nanogenerator by repeated sliding. The VOC species and their concentrations were well-quantified from the wavelength and intensity of spectra signals with the enhancement from plasma. Furthermore, machine learning has visualized the relationship of different VOCs in the mixture, which demonstrated the feasibility of the VOC identification to mimic patients.
Human–machine interfaces are essential components between various human and machine interactions such as entertainment, robotics control, smart home, virtual/augmented reality, etc. Recently, various ...triboelectric‐based interfaces have been developed toward flexible wearable and battery‐less applications. However, most of them exhibit complicated structures and a large number of electrodes for multidirectional control. Herein, a bio‐inspired spider‐net‐coding (BISNC) interface with great flexibility, scalability, and single‐electrode output is proposed, through connecting information‐coding electrodes into a single triboelectric electrode. Two types of coding designs are investigated, i.e., information coding by large/small electrode width (L/S coding) and information coding with/without electrode at a predefined position (0/1 coding). The BISNC interface shows high scalability with a single electrode for detection and/or control of multiple directions, by detecting different output signal patterns. In addition, it also has excellent reliability and robustness in actual usage scenarios, since recognition of signal patterns is in regardless of absolute amplitude and thereby not affected by sliding speed/force, humidity, etc. Based on the spider‐net‐coding concept, single‐electrode interfaces for multidirectional 3D control, security code systems, and flexible wearable electronics are successfully developed, indicating the great potentials of this technology in diversified applications such as human–machine interaction, virtual/augmented reality, security, robotics, Internet of Things, etc.
A bio‐inspired spider‐net‐coding (BISNC) interface is developed with information‐coding on a single triboelectric electrode. Thereby multidirectional sensing/control using the single‐electrode interface is achieved. The device shows excellent reliability and robustness since signal recognition is in regardless of absolute amplitude and thus not affected by sliding speed/force and humidity. Furthermore, it is highly scalable for more directions sensing and diverse applications.
Rapid developments of robotics and virtual reality technology are raising the requirements of more advanced human-machine interfaces for achieving efficient parallel control. Exoskeleton as an ...assistive wearable device, usually requires a huge cost and complex data processing to track the multi-dimensional human motions. Alternatively, we propose a triboelectric bi-directional sensor as a universal and cost-effective solution to a customized exoskeleton for monitoring all of the movable joints of the human upper limbs with low power consumption. The corresponding movements, including two DOF rotations of the shoulder, twisting of the wrist, and the bending motions, are detected and utilized for controlling the virtual character and the robotic arm in real-time. Owing to the structural consistency between the exoskeleton and the human body, further kinetic analysis offers additional physical parameters without introducing other types of sensors. This exoskeleton sensory system shows a great potential of being an economic and advanced human-machine interface for supporting the manipulation in both real and virtual worlds, including robotic automation, healthcare, and training applications.
Sign language recognition, especially the sentence recognition, is of great significance for lowering the communication barrier between the hearing/speech impaired and the non-signers. The general ...glove solutions, which are employed to detect motions of our dexterous hands, only achieve recognizing discrete single gestures (i.e., numbers, letters, or words) instead of sentences, far from satisfying the meet of the signers' daily communication. Here, we propose an artificial intelligence enabled sign language recognition and communication system comprising sensing gloves, deep learning block, and virtual reality interface. Non-segmentation and segmentation assisted deep learning model achieves the recognition of 50 words and 20 sentences. Significantly, the segmentation approach splits entire sentence signals into word units. Then the deep learning model recognizes all word elements and reversely reconstructs and recognizes sentences. Furthermore, new/never-seen sentences created by new-order word elements recombination can be recognized with an average correct rate of 86.67%. Finally, the sign language recognition results are projected into virtual space and translated into text and audio, allowing the remote and bidirectional communication between signers and non-signers.
Application of two major classes of CO2 gas sensors, i.e., electrochemical and nondispersive infrared is predominantly impeded by the poor selectivity and large optical interaction length, ...respectively. Here, a novel “hybrid metamaterial” absorber platform is presented by integrating the state‐of‐the‐art complementary metal–oxide–semiconductor compatible metamaterial with a smart, gas‐selective‐trapping polymer for highly selective and miniaturized optical sensing of CO2 gas in the 5–8 µm mid‐IR spectral window. The sensor offers a minimum of 40 ppm detection limit at ambient temperature on a small footprint (20 µm by 20 µm), fast response time (≈2 min), and low hysteresis. As a proof‐of‐concept, net absorption enhancement of 0.0282%/ppm and wavelength shift of 0.5319 nm ppm−1 are reported. Furthermore, the gas‐ selective smart polymer is found to enable dual‐mode multiplexed sensing for crosschecking and validation of gas concentration on a single platform. Additionally, unique sensing characteristics as determined by the operating wavelength and bandwidth are demonstrated. Also, large differential response of the metamaterial absorber platform for all‐optical monitoring is explored. The results will pave the way for a physical understanding of metamaterial‐based sensing when integrated with the mid‐IR detector for readout and extending the mid‐IR functionalities of selective polymers for the detection of technologically relevant gases.
A novel hybrid metamaterial absorber platform is presented by integrating the state‐of‐the‐art complementary metal–oxide–semiconductor compatible metamaterial with a smart, gas‐selective‐trapping polymer for highly selective and miniaturized optical sensing of CO2 gas in the 5–8 µm mid‐IR spectral window.
Acoustic energy transfer is a promising energy harvesting technology candidate for implantable biomedical devices. However, it does not show competitive strength for enabling self-powered implantable ...biomedical devices due to two issues - large size of bulk piezoelectric ultrasound transducers and output power fluctuation with transferred distance due to standing wave. Here we report a microelectromechanical systems (MEMS) based broadband piezoelectric ultrasonic energy harvester (PUEH) to enable self-powered implantable biomedical devices. The PUEH is a microfabricated lead zirconate titanate (PZT) diaphragm array and has wide operation bandwidth. By adjusting frequency of the input ultrasound wave within the operation bandwidth, standing wave effect can be minimized for any given distances. For example, at 1 cm distance, power density can be increased from 0.59 μW/cm(2) to 3.75 μW/cm(2) at input ultrasound intensity of 1 mW/cm(2) when frequency changes from 250 to 240 kHz. Due to the difference of human body and manual surgical process, distance fluctuation for implantable biomedical devices is unavoidable and it strongly affects the coupling efficiency. This issue can be overcome by performing frequency adjustment of the PUEH. The proposed PUEH shows great potential to be integrated on an implanted biomedical device chip as power source for various applications.
A piezoelectric micromachined ultrasonic transducer (pMUT) has enabled numerous exciting ultrasonic applications. However, residual stress and initial buckling may worsen the transmitting sensitivity ...of a pMUT, and also limit its application and commercialization. In this paper, we report a new innovative pMUT with a perfectly flat membrane, i.e., zero-bending membrane. Leveraging on the stress-free AlN thin film, framelike top electrode layout, and integrated vacuum cavity, the initial deflection of suspended membrane is significantly suppressed to only 0.005%. The transmitting sensitivity of the zero-bending pMUT is measured as 123 nm/V at a resonant frequency of 2.21 MHz, which is 450% higher than that of the reference pMUT with slightly non-zero initial deflection. Compared with the simulation results, the measured data of zero-bending pMUT achieve 94.5% of its ideal transmitting sensitivity. It is solid evidence that our approach is an effective and reliable way to overcome the residual stress and the initial buckling issue.
The need of self-powered sensors and self-sustainable micro-/nano-systems is increasing for smart home applications. With the aid of the fifth-generation (5G) wireless communication and the ...artificial intelligence (AI) technology, numerous sensors can form an artificial intelligence of things (AIoT) system with a cloud computing server to collect, store, process, analyze data, and control the system. In this review, we briefly introduce the major sensor transducing mechanisms and the corresponding representative sensors. Then we emphasize the discussion of triboelectric sensors and their use as various types of human machine interfaces (HMIs). Regarding integrated self-sustainable systems with energy storage function for more general application scenarios, we present the recent advances of integration of triboelectric nanogenerator with supercapacitors, lithium-ion batteries, and solar cells. The development of materials and configurations with novel functionalities to improve the system performance are discussed. We present the state-of-the-art works based on the synergy between wearable sensors and AI technology, highlighting the system-level function of analyzing abundant sensory data, recognizing events, and making decisions accordingly. We wrap up the review by providing our perspectives of future development of self-powered sensors and self-sustainable micro-/nano-systems towards improved wearability, multifunctionality, better self-sustainability via multi-domain energy harvesting and storage technology integration, and higher-level intelligence for complex scenarios.
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•Evolution from self-powered sensors to self-sustainable micro-/nano-systems for 5G smart homes in the AIoT era was reviewed.•Recent advances of self-powered physical sensors, chemical sensors, and human-machine interfaces were presented.•System integration of TENGs and energy storages towards self-sustainable micro-/nano-systems was summarized.•Fusion of AIoT and self-sustainable micro-/nano-systems was highlighted.
Pressure sensors with flexibility are important functional components as the interface between the mechanical motion and electric signal in healthcare monitoring system. Conventional triboelectric ...based pressure sensors have advantages of simple structure configuration and self-powered sensing mechanism. However, the contact-separation working principle requires macro-scale air gap and the performance is largely affected by the separation distance, which is not suitable for conformal human motion sensing. Hence in this paper, we report a flexible microfluidic pressure sensor based on liquid-solid interface triboelectrification when liquid flows in a microfluidic channel. The proposed microfluidic pressure sensor is able to have a conformal contact with human skin and no separation gap is required due to the microfluidic chamber and channel design. It is capable of working in two sensing mechanisms – triboelectric mechanism and capacitive mechanism. Triboelectric mechanism can be used to detect the dynamic pressure change on device without external power supply. Capacitive mechanism can be adopted as complementary sensing mechanism to detect both dynamic pressure change and static pressure. The proposed microfluidic pressure sensor can monitor both the magnitude and frequency of the pressure applied on the device simultaneously. Besides, the device can be integrated with microfluidic system as a self-powered flow rate sensor. Moreover, it can be conformally attached on human finger for finger bending degree and bending frequency detection. The proposed microfluidic pressure sensor offers more usage flexibility for flow rate, finger motion monitoring and the potentials for more complex human motion monitoring applications.
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•Self-powered liquid triboelectric microfluidic pressure sensor reported for the first time.•Conformal contact with human skin and no separation gap is required.•Two sensing mechanisms – triboelectric mechanism and capacitive mechanism.•Triboelectric mechanism shows better sensitivity and linear sensing range.•Integration ability with microfluidic system as self-powered flow rate sensor.
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