Publications

Abstract There is an increasing interest to develop a next generation of touch pads that require stretchability and biocompatibility to allow their integration with a human body, and even to mimic the self‐healing behavior with fast functionality recovery upon damage. However, most touch pads are developed based on stiff and brittle electrodes with the lack of the important nature of self‐healing. Polyzwitterion–clay nanocomposite hydrogels as a soft, stretchable, and transparent ionic conductor with transmittance of 98.8% and fracture strain beyond 1500% are developed, which can be used as a self‐healing human–machine interactive touch pad with pressure‐sensitive adhesiveness on target substrates. A surface‐capacitive touch system is adopted to sense a touched position. Finger positions are perceived during both point‐by‐point touch and continuous moving. Hydrogel touch pads are adhered to curved or flat insulators, with the high‐resolution and self‐healable input functions demonstrated by drawing, writing, and playing electronic games.

Abstract In the swiftly progressing landscape of wearable electronics and the Internet of Things (IoTs), there is a burgeoning demand for devices that are lightweight, cost‐effective, and self‐powered. In this study, a self‐powered bidirectional knee joint motion monitoring system is introduced, leveraging a dual ratchet sensing (DRS) system fabricated using 3D printing technology. This approach offers substantial economic and portability benefits. The DRS system is engineered to harness the negative work generated from knee joint movements to power commercial electronic devices, obviating the need for additional metabolic energy from the human body. By synergizing the DRS with virtual reality technology, it becomes feasible to monitor knee joint movements in real‐time with remarkable accuracy, presenting a novel avenue for the integration of digital twin technology. Through the amalgamation of convolutional neural network machine learning algorithms with Bayesian optimization techniques, the DRS system can discern up to 97% of knee joint movements, paving the way for innovative applications in smart rehabilitation and healthcare.

Abstract The ϵ‐Fe 2 O 3 phase is commonly considered an intermediate phase during thermal treatment of maghemite (γ‐Fe 2 O 3 ) to hematite (α‐Fe 2 O 3 ). The routine method of synthesis for ϵ‐Fe 2 O 3 crystals uses γ‐Fe 2 O 3 as the source material and requires dispersion of γ‐Fe 2 O 3 into silica, and the obtained ϵ‐Fe 2 O 3 particle size is rather limited, typically under 200 nm. In this paper, by using a pulsed laser deposition method and Fe 3 O 4 powder as a source material, the synthesis of not only one‐dimensional Fe 3 O 4 nanowires but also high‐yield ϵ‐Fe 2 O 3 nanowires is reported for the first time. A detailed transmission electron microscopy (TEM) study shows that the nanowires of pure magnetite grow along [111] and <211> directions, although some stacking faults and twins exist. However, magnetite nanowires growing along the <110> direction are found in every instance to accompany a new phase, ϵ‐Fe 2 O 3 , with some micrometer‐sized wires even fully transferring to ϵ‐Fe 2 O 3 along the fixed structural orientation relationship, (001) ∥ (111) , [010] ∥ <110> . Contrary to generally accepted ideas regarding epsilon phase formation, there is no indication of γ‐Fe 2 O 3 formation during the synthesis process; the phase transition may be described as being from Fe 3 O 4 to ϵ‐Fe 2 O 3 , then to α‐Fe 2 O 3 . The detailed structural evolution process has been revealed by using TEM. 120° rotation domain boundaries and antiphase boundaries are also frequently observed in the ϵ‐Fe 2 O 3 nanowires. The observed ϵ‐Fe 2 O 3 is fundamentally important for understanding the magnetic properties of the nanowires.

With a promising prospect of light-emitting diodes as an attractive alternative to conventional light sources, remaining challenges still cannot be addressed owing to their limited efficiency. Among the continued scientific efforts, significant improvement on the emission efficiency has been achieved via either piezo-phototronic effect-based strain modulation or resonant excitation of plasmons in metallic nanostructures. Here, we present the investigation on the coupling process between piezo-phototronic effect and localized surface plasmonic resonance for enhancing the photoluminescence of InGaN/GaN quantum wells coated with Ag nanoparticles. The underlying physical mechanism of experimental results originates from tuning plasmonic resonance controlled by the shift of emission wavelength via piezo-phototronic effect, and it is further confirmed with the support of theoretical calculations. As a result, our research provides an approach to the integration of plasmonics with piezo-phototronic effect and brings widespread applications to high-efficiency artificial lighting, on-chip integrated plasmonic circuits, subwavelength optical communication, and micro-optoelectronic mechanical systems.

Triboelectric nanogenerators (TENGs) are demonstrated to possess great superiority in the field of low-frequency and high-entropy energy harvesting. Here, a kind of friction material, super-light clay (SLC), with outstanding stretchability and shape/size changeability is introduced to develop contact-separation triboelectric nanogenerators (SLC-TENGs), which exhibit outstanding flexible, shape-changeable, and adaptable properties but simple preparation processes. A high and stable electrical output can be achieved from the simple-structured SLC-TENG. The peak power density of the SLC-TENG output reaches up to 0.33 W/m2 under an effective contact with an area of 9 cm2 and an external load resistance of 50 MΩ. In addition, a balloon-structured TENG was also prepared with the filling of several SLC balls. The electrical signals can be generated even just by a slight shaking, revealing great application potential in the Internet of Things systems and self-powered sensors by energy harvesting from wind, ocean, human body movements, etc.

Generation of direct current (DC) from mechanical kinetic energies is crucial for realizing self-powered wearable electronics. Here, we report a flexible textile-based DC generator based on the tribovoltaic effect at a dynamic metal-semiconducting polymer interface. The tribovoltaic effect refers to a phenomenon in which an energy "quantum" is released once an atom–atom bond is formed at the dynamic interface of two contacting materials; such released "binding" energy excites electron–hole pairs at metal–semiconductor interfaces or semiconductor–semiconductor pn junctions. This textile DC generator, based on the dynamic Schottky junction between an Al slider and a poly(3,4-ethylenedioxythiophene)-coated textile, can output a voltage of approximately 0.45–0.70 V. The voltage and current can be increased by simply connecting multiple generators in series or in parallel. Seven generators in series can power an electronic watch constantly without any conditioning circuit. These findings offer an efficient strategy for harvesting mechanical energies and realizing self-powered electronics.