Publications

Tactile perception includes the direct response of tactile corpuscles to environmental stimuli and psychological parameters associated with brain recognition. To date, several artificial haptic-based sensing techniques can accurately measure physical stimuli. However, quantifying the psychological parameters of tactile perception to achieve texture and roughness identification remains challenging. Here, we developed a smart finger with surpassed human tactile perception, which enabled accurate identification of material type and roughness through the integration of triboelectric sensing and machine learning. In principle, as each material has different capabilities to gain or lose electrons, a unique triboelectric fingerprint output will be generated when the triboelectric sensor is in contact with the measured object. The construction of a triboelectric sensor array could further eliminate interference from the environment, and the accuracy rate of material identification was as high as 96.8%. The proposed smart finger provides the possibility to impart artificial tactile perception to manipulators or prosthetics.

Compound semiconductor/isolator (ZnS/silica) core/shell nanocables have been used to fabricate single nanowire-based field effect transistors. Using the surface-adsorbed charged molecules as the gate, the nanocable-based devices show potential for label-free, real-time, and sensitive detection of biological species. After chemical modification, amine- and oxide-functionalized nanocables exhibit linear pH-dependent conductance, which could be elucidated in terms of the changes of surface charge during protonation and deprotonation. Selective biological recognition of nanocable sensors has been demonstrated using biotinylation.

Textile-based triboelectric nanogenerators (TENG) that can effectively harvest biomechanical energy and sense multifunctional posture and movement have a wide range of applications in next-generation wearable and portable electronic devices. Hence, bulk production of fine yarns with high triboelectric output through a continuous manufacturing process is an urgent task. Here, an ultralight single-electrode triboelectric yarn (SETY) with helical hybridized nano-micro core–shell fiber bundles is fabricated by a facile and continuous electrospinning technology. The obtained SETY device exhibits ultralightness (0.33 mg cm–1), extra softness, and smaller size (350.66 μm in diameter) compared to those fabricated by conventional fabrication techniques. Based on such a textile-based TENG, high energy-harvesting performance (40.8 V, 0.705 μA cm–2, and 9.513 nC cm–2) was achieved by applying a 2.5 Hz mechanical drive of 5 N. Importantly, the triboelectric yarns can identify textile materials according to their different electron affinity energies. In addition, the triboelectric yarns are compatible with traditional textile technology and can be woven into a high-density plain fabric for harvesting biomechanical energy and are also competent for monitoring tiny signals from humans or insects.

Due to the non-centrosymmetric crystal structures, wurtzite family semiconducting materials possess piezoelectric properties and exhibit polarizations along certain directions upon straining. Utilizing strain-induced piezoelectric polarization charges to modulate the energy band structures and thus to tune/control the transport processes of charge carriers is referred to as the piezotronic effect. Distinct from the previous studies of c-axis GaN nanowires, here we systematically study the piezotronic-effect-induced modifications of energy band structures and the corresponding influence on electronic transport properties of a-axis GaN nanobelts. The physical mechanism is carefully illustrated and further confirmed by theoretical simulations via finite element analysis. The spatial distributions of local carrier concentration and the energy band diagrams of a-axis GaN under various straining conditions are calculated. This work provides a thorough understanding of strain-gated transport properties of a-axis GaN piezotronic transistors and its future applications in semiconductor devices.

The heat is on: Surface sublimation and shape transformation of silver cubes, enclosed by {100} surfaces and about 100nm in size, are examined by in situ transmission electron microscopy (see picture). High-index surfaces, such as {110}, of face-centered cubic metals are more stable when the temperature is close to the melting point.

Abstract High-electron-mobility transistors (HEMTs) are a promising device in the field of radio frequency and wireless communication. However, to unlock the full potential of HEMTs, the fabrication of large-size flexible HEMTs is required. Herein, a large-sized (> 2 cm 2 ) of AlGaN/AlN/GaN heterostructure-based HEMTs were successfully stripped from sapphire substrate to a flexible polyethylene terephthalate substrate by an electrochemical lift-off technique. The piezotronic effect was then induced to optimize the electron transport performance by modulating/tuning the physical properties of two-dimensional electron gas (2DEG) and phonons. The saturation current of the flexible HEMT is enhanced by 3.15% under the 0.547% tensile condition, and the thermal degradation of the HEMT was also obviously suppressed under compressive straining. The corresponding electrical performance changes and energy diagrams systematically illustrate the intrinsic mechanism. This work not only provides in-depth understanding of the piezotronic effect in tuning 2DEG and phonon properties in GaN HEMTs, but also demonstrates a low-cost method to optimize its electronic and thermal properties.

Growing experimental evidence suggests that physical cues play an important role in regulating the fate of stem cells and stimulating their differentiation behavior. We report here that static pressure enables the differentiation of rat bone marrow-derived mesenchymal stem cells (MSCs) into neural-like cells within several hours in the absence of disruptive bio-factors or chemicals. The realization of such differentiation is supported by the observation of characteristic morphology of neural-like cells with neurites, and an up-regulated expression level of neural-specific markers. Our finding also demonstrates the utility of the static pressure-based approach for in situ and specifically localized creation of neural cell systems, thereby providing profound implications for developing therapeutic application of stem cells.

Small molecules and antibodies each have advantages and limitations as therapeutics. Here, we present for the first time to our knowledge, the structure-guided design of as small molecule-antibody hybrids that offer dual recognition of a single target by both a small molecule and an antibody, using DPP-IV enzyme as a proof of concept study. Biochemical characterization demonstrates that the chemibodies present superior DPP-IV inhibition compared to either small molecule or antibody component alone. We validated our design by successfully solving a co-crystal structure of a chemibody in complex with DPP-IV, confirming specific binding of the small molecule portion at the interior catalytic site and the Fab portion at the protein surface. The discovery of chemibodies presents considerable potential for novel therapeutics that harness the power of both small molecule and antibody modalities to achieve superior specificity, potency, and pharmacokinetic properties.

The finger-sized FDC-TENG can light up 99 commercial bulbs and 1053 LEDs and drive watches and calculators easily and directly by sliding it manually.

Abstract Deploying triboelectric nanogenerator (TENG) units on and below the water surface has been a conventional method for harvesting wave energy. However, this approach restricts the TENG's amplitude to that of the water waves, limiting the actual offshore output. Here, a new method of placing TENG units above the water surface using a wave amplitude amplifier is reported. This addresses the issue of insufficient amplitude in traditional wave energy TENGs and achieves higher electrical output performance in real offshore conditions. Moreover, the innovative four‐helix TENG (FH‐TENG), designed with special pattern cutting and bridging techniques, eliminates the need for internal wires, foundational frameworks, and counterweights. Results show that FH‐TENG placed on the amplitude amplifier achieves over a 76% increase in amplitude and a 235% enhancement in charge output compared to FH‐TENG floating directly on the water surface, and the maximum output voltage, transferred charge and output current reach 246 V, 7.9 µC, and 156.1 µA, respectively. Importantly, when deployed in real marine environments, this system generates more electric energy than in a lab pool under the same peak wave height, providing a reliable power supply solution. This work establishes a precedent for deploying lightweight wave energy TENGs above the water surface.

A vibration sensor is usually designed to measure the vibration frequency but disregard the vibration amplitude, which is rather challenging to be quantified due to the requirement of linear response. Here, we show the application of triboelectric nanogenerator (TENG) as a self-powered tool for quantitative measurement of vibration amplitude based on an operation mode, the contact-mode freestanding triboelectric nanogenerator (CF-TENG). In this mode, the triboelectrically charged resonator can be agitated to vibrate between two stacked stationary electrodes. Under the working principle with a constant capacitance between two electrodes, the amplitudes of the electric signals are proportional to the vibration amplitude of the resonator (provided that the resonator plate is charged to saturation), which has been illuminated both theoretically and experimentally. Together with its capability in monitoring the vibration frequency, the CF-TENG appears as the triboelectrification-based active sensor that can give full quantitative information about a vibration. In addition, the CF-TENG is also demonstrated as a power source for electronic devices.

The piezo‐phototronic effect is about the enhanced separation, transport, and recombination of the photogenerated carriers using the piezoelectric polarization charges present in piezoelectric‐semiconductor materials. Here, it is presented that the piezo‐phototronic effect can be effectively applied to improve the relative conversion efficiency of a flexible solar cell based on n‐ZnO/p‐SnS core–shell nanowire array for 37.3% under a moderate vertical pressure. The performance of the solar cell can be effectively enhanced by a gentle bending of the device, showing its potential for application in curly geometries. This study not only adds further understanding about the concept of increasing solar energy conversion efficiency via piezo‐phototronic effect, but also demonstrates the great potential of piezo‐phototronic effect in the application of large‐scale, flexible, and lightweight nanowire array solar cells.