Publications

The output performance of triboelectric nanogenerators (TENGs) largely depends on the density of electrons on the surface of the triboelectric materials, which is usually generated by the direct contact of two solid materials. Here, a novel method is proposed to regulate the surface charges of materials without physical contact. A laser-tunable noncontact triboelectric nanogenerator (LTNC-TENG) is fabricated, enabling the dynamic regulation of the surface states of materials through laser irradiation to optimize the performance of TENGs. In the experiment, TiO₂, SiO₂, and VO₂ LTNC-TENGs are designed and prepared. The results show that under low-energy laser irradiation, the open-circuit voltage (<i>V</i>_OC) and short-circuit transferred charge (<i>Q</i>_SC) increase, primarily due to the enhancement of the surface state energy levels induced by laser irradiation. As the laser energy increases beyond the laser-induced damage threshold (LIDT) of the films, induced damage occurs, generating abundant high-temperature plasma and resulting in decreased <i>V</i>_OC and <i>Q</i>_SC. Building upon these findings, a single-electrode mode LTNC-TENG is developed where voltage jumps occur when laser energy exceeds the film's LIDT. Furthermore, an electron cloud-potential well model is proposed, describing the approach of atoms from two different materials under laser irradiation without direct contact. This model elucidates the detailed mechanism of laser-induced charge transfer and reveals the "precursor" process of contact electrification. This study contributes to a deeper understanding of the underlying mechanisms of contact electrification and provides a theoretical foundation for the development of more advanced and noncontact TENGs, with largely enhanced lifetime.

Abstract Robots that can move, feel, and respond like organisms will bring revolutionary impact to today's technologies. Soft robots with organism‐like adaptive bodies have shown great potential in vast robot–human and robot–environment applications. Developing skin‐like sensory devices allows them to naturally sense and interact with environment. Also, it would be better if the capabilities to feel can be active, like real skin. However, challenges in the complicated structures, incompatible moduli, poor stretchability and sensitivity, large driving voltage, and power dissipation hinder applicability of conventional technologies. Here, various actively perceivable and responsive soft robots are enabled by self‐powered active triboelectric robotic skins (tribo‐skins) that simultaneously possess excellent stretchability and excellent sensitivity in the low‐pressure regime. The tribo‐skins can actively sense proximity, contact, and pressure to external stimuli via self‐generating electricity. The driving energy comes from a natural triboelectrification effect involving the cooperation of contact electrification and electrostatic induction. The perfect integration of the tribo‐skins and soft actuators enables soft robots to perform various actively sensing and interactive tasks including actively perceiving their muscle motions, working states, textile's dampness, and even subtle human physiological signals. Moreover, the self‐generating signals can drive optoelectronic devices for visual communication and be processed for diverse sophisticated uses.

An unstable mechanical structure that can self-balance when perturbed is a superior choice for vibration energy harvesting and vibration detection. In this work, a suspended 3D spiral structure is integrated with a triboelectric nanogenerator (TENG) for energy harvesting and sensor applications. The newly designed vertical contact-separation mode TENG has a wide working bandwidth of 30 Hz in low-frequency range with a maximum output power density of 2.76 W/m(2) on a load of 6 MΩ. The position of an in-plane vibration source was identified by placing TENGs at multiple positions as multichannel, self-powered active sensors, and the location of the vibration source was determined with an error less than 6%. The magnitude of the vibration is also measured by the output voltage and current signal of the TENG. By integrating the TENG inside a buoy ball, wave energy harvesting at water surface has been demonstrated and used for lighting illumination light, which shows great potential applications in marine science and environmental/infrastructure monitoring.

Sustainable high-voltage TENG (SH-TENG) based on charge accumulation strategy can provide an unprecedented high voltage output.

A flexible and transparent lead-free triangular-belt ZnSnO3 nanogenerator is demonstrated. When a mechanical deformation of ≈0.1% is applied to the triangular-belt ZnSnO3 nanogenerator, the output voltage and current reached 5.3 V and 0.13 μA, respectively, which indicated a maximum output power density of ≈11 μW·cm−3. This is the highest output power that has been demonstrated by lead-free ZnSnO3 triangular-belts. Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Piezotronics and piezophototronics are emerging fields by coupling piezoelectric, semiconductor, and photon excitation effects for achieving high-performance strain-gated sensors, LEDs, and solar cells. The built-in piezoelectric potential effectively controls carrier transport characteristics in piezoelectric semiconductor materials, such as ZnO, GaN, InN, CdS, and monolayer MoS2. In this paper, a topological insulator piezotronic transistor is investigated theoretically based on a HgTe/CdTe quantum well. The conductance, ON/OFF ratio, and density of states have been studied at various strains for the topological insulator piezotronic transistor. The ON/OFF ratio of conductance can reach up to 1010 with applied strain. The properties of the topological insulator are modulated by piezoelectric potential, which is the result of the piezotronic effect on quantum states. The principle provides a method for developing high-performance piezotronic devices based on a topological insulator.

Sphingosine kinases (SPHKs) are enzymes that phosphorylate the lipid sphingosine, leading to the formation of sphingosine-1-phosphate (S1P). In addition to the well established role of extracellular S1P as a mitogen and potent chemoattractant, SPHK activity has been postulated to be an important intracellular regulator of apoptosis. According to the proposed rheostat theory, SPHK activity shifts the intracellular balance from the pro-apoptotic sphingolipids ceramide and sphingosine to the mitogenic S1P, thereby determining the susceptibility of a cell to apoptotic stress. Despite numerous publications with supporting evidence, a clear experimental confirmation of the impact of this mechanism on tumor cell viability in vitro and in vivo has been hampered by the lack of suitable tool reagents. Utilizing a structure based design approach, we developed potent and specific SPHK1/2 inhibitors. These compounds completely inhibited intracellular S1P production in human cells and attenuated vascular permeability in mice, but did not lead to reduced tumor cell growth in vitro or in vivo. In addition, siRNA experiments targeting either SPHK1 or SPHK2 in a large panel of cell lines failed to demonstrate any statistically significant effects on cell viability. These results show that the SPHK rheostat does not play a major role in tumor cell viability, and that SPHKs might not be attractive targets for pharmacological intervention in the area of oncology.

Abstract The most common size range of particulate matter (PM) in tobacco smoke is 1.0 to 5.0 microns; however, a high number of the most harmful PM is as small as 0.5 micron that is a serious threat to human health, and it is difficult to remove. There is an urgent need to develop a new purification technology for high‐efficiency removing tobacco smoke with easily construction and low cost. Here, a method of self‐powered high‐voltage recharging system is demonstrated by designing biomimetic hairy‐contact triboelectric nanogenerator (BHC‐TENG) for long‐lasting adsorption with a wide range from PM 0.5 to PM 10. The open‐circuit voltage of BHC‐TENGs reaches 8.42 KV, which can continuously charge injection to the melt‐blown fabric, whose surface potential is able to maintain nearly 260 V level and create a uniform electrostatic adsorption field on the surface. This high‐voltage recharging system reduces the concentration of PMs to World Health Organization (WHO) standards, maintaining the purification efficiency of PM 0.5– PM 10 persistently over 90%.

Modern cryptography increasingly employs random numbers generated from physical sources in lieu of conventional software-based pseudorandom numbers, primarily owing to the great demand of unpredictable, indecipherable cryptographic keys from true random numbers for information security. Thus, far, the sole demonstration of true random numbers has been generated through thermal noise and/or quantum effects, which suffers from expensive and complex equipment. In this paper, we demonstrate a method for self-powered creation of true random numbers by using triboelectric technology to collect random signals from nature. This random number generator based on coupled triboelectric and electrostatic induction effects at the liquid–dielectric interface includes an elaborately designed triboelectric generator (TENG) with an irregular grating structure, an electronic–optical device, and an optical–electronic device. The random characteristics of raindrops are harvested through TENG and consequently transformed and converted by electronic–optical device and an optical–electronic device with a nonlinear characteristic. The cooperation of the mechanical, electrical, and optical signals ensures that the generator possesses complex nonlinear input–output behavior and contributes to increased randomness. The random number sequences are deduced from final electrical signals received by an optical–electronic device using a familiar algorithm. These obtained random number sequences exhibit good statistical characteristics, unpredictability, and unrepeatability. Our study supplies a simple, practical, and effective method to generate true random numbers, which can be widely used in cryptographic protocols, digital signatures, authentication, identification, and other information security fields.

E-O Sensors are being developed for a variety of Military Systems Applications. These include UV, Visible, SWIR, MWIR and LWIR Nano Sensors. In this paper, we will discuss growth and characterization of ZnO Nanowires on a variety of substrates that include Silicon, ZnO and flexible substrates. The critical technologies being developed include ZnO nanostructures with wide band gap for UV detection for a variety of threat warning applications. We will present experimental results on the structural, electrical and optical properties of ZnO nanowire for UV detectors. Experimental results on ZnO based nanostructures demonstrate enhanced UV sensitivity and path forward for larger arrays.

Abstract Combination flexible and stretchable textiles with self-powered sensors bring a novel insight into wearable functional electronics and cyber security in the era of Internet of Things. This work presents a highly flexible and self-powered fully fabric-based triboelectric nanogenerator (F-TENG) with sandwiched structure for biomechanical energy harvesting and real-time biometric authentication. The prepared F-TENG can power a digital watch by low-frequency motion and respond to the pressure change by the fall of leaves. A self-powered wearable keyboard (SPWK) is also fabricated by integrating large-area F-TENG sensor arrays, which not only can trace and record electrophysiological signals, but also can identify individuals' typing characteristics by means of the Haar wavelet. Based on these merits, the SPWK has promising applications in the realm of wearable electronics, self-powered sensors, cyber security, and artificial intelligences.