Search

In this paper, we investigate rewards attacks on stochastic multi-armed bandit algorithms with non-stationary environment. The attacker's goal is to force the victim algorithm to choose a suboptimal arm most of the time while incurring a small attack cost. We consider three increasingly general attack scenarios, each of which has different assumptions about the environment, victim algorithm and information available to the attacker. We propose three attack strategies, one for each considered scenario, and prove that they are successful in terms of expected target arm selection and attack cost. We also propose a defense non-stationary algorithm that is able to defend any attacker whose attack cost is bounded by a budget, and prove that it is robust to attacks. The simulation results validate our theoretical analysis.

Harvesting continuously water wave energy for on-site power generation offers a promising solution to address the offshore energy shortage. However, challenges arise in ocean wave energy harvesting during low-level sea states. Here, we propose a spring-coupled enhanced hybrid nanogenerator (SC-EHG), wherein the synergistic effects of gravity and elastic force allow it to achieve remarkable power generation capacity under low-level excitation. At a frequency of 0.1 Hz, the SC-EHG becomes operational at a tilted angle of merely 2 °, with sensitivity and energy harvesting direction range improved by sixfold and threefold, respectively, in comparison to configurations lacking a spring coupler. In the real ocean, under wave conditions characterized by a significant frequency (fs) of 0.31 Hz and a significant wave height (Hs) of 7.87 cm, the output frequency of the SC-EHG reaches up to 0.75 Hz, an effective increase of 2.41 times. At this point, the maximum transferred charge (1.43 μC) and maximum open-circuit voltage (422.6 V) of a TENG module approximate the output values recorded under laboratory wave conditions (fs= 0.82 Hz, Hs= 6.17 cm). Under ocean wave conditions of fs= 0.21 Hz and Hs= 4.52 cm, the SC-EHG successfully powered a marine sensing system, enabling 1024 m of long-distance wireless communication by charging a 30 mF capacitor to 8.35 V. The robust performance of the SC-EHG at low level sea states (≤ 1) offers significant support for the establishment of a sustainable marine Internet of Things.

In this study, Al–20Si alloy is modified by appending trace Sr–Sc–Ce nanoparticles and ultrasonic vibration processing (UVP). The consequences indicate that its microstructure is significantly refined and its mechanical characteristics are improved. The effect of the favorable refinements is achieved by appending 0.2% Sr–0.15% Sc–0.3% Ce and performing UVP. The primary Si is the minimum, the grain roundness coefficient and the strength of extension are the maximum, and the spheroidizing effect of α‐Al is the best. The elongation and hardness are the highest when 0.4% Ce is appended. The research consequences afford a reasonable process scheme for manufacturing high‐quality wear‐resistant material of the automotive and aerospace industries. Herein, the effect of the combination of trace Sr–Sc–Ce modifier and ultrasonic vibration processing is tested on the grain refinement and spheroidization of Al–20Si, and the improvement of mechanical characteristics is more promoted. Thus, a reasonable process scheme is afforded for manufacturing high‐quality wear‐resistant material of the automotive and aerospace industries.

It is known that contact-electrification (or triboelectrification) usually occurs between two different materials, which could be explained by several models for different materials systems (Adv. Mater. 2018, 30, 1706790; Adv. Mater. 2018, 30, 1803968). But contact between two pieces of the chemically same material could also result in electrostatic charges, although the charge density is rather low, which is hard to understand from a physics point of view. In this paper, by preparing a contact-separation mode triboelectric nanogenerator using two pieces of an identical material, the direction of charge transfer during contact-electrification is studied regarding its dependence on curvatures of the sample surfaces. For materials such as polytetrafluoroethylene, fluorinated ethylene propylene, Kapton, polyester, and nylon, the positive curvature surfaces are net negatively charged, while the negative curvature surfaces tend to be net positively charged. Further verification of the above-mentioned trends was obtained under vacuum (∼1 Pa) and higher temperature (≤358 K) conditions. Based on the received data acquired for gentle contacting cases, we propose a curvature-dependent charge transfer model by introducing curvature-induced energy shifts of the surface states. However, this model is subject to be revised if the mutual contact mode turns into a sliding mode or more complicated hard-pressed contact mode, in which a rigorous contact between the two pieces of the same material could result in nanoscale damage/fracture and possible species transfer. Our study provides a primitive step toward understanding the basics of contact-electrification.

Although various triboelectric nanogenerators (TENGs) and hybrid ocean kinetic energy harvesters (OKEHs) have been devised for blue energy harvesting, the lack of studies in the real ocean has hindered their progress. Here, a high-sensitivity modular shuttle-like hybrid nanogenerator (MSHG) is prepared, comprising contact-separation TENG, piezoelectric nanogenerator (PENG), and electromagnetic generator (EMG) components. Its acceleration feature and electrical performance were systematically investigated under various conditions, from laboratory setups to real ocean waves. The  MSHG responds sensitively to low-level excitations and exhibits robust energy harvesting capability in the ocean. Statistical analysis shows that its most probable output frequency reaches 0.83Hz, which is about four times higher than the main frequency of the ocean wave (0.1-0.2Hz). A 12-integrated MSHG system effectively harvests ocean wave energy to power a water-quality detector, while its most probable acceleration amplitude is approximately 24% of the maximum in a simulated linear motor motion and 57% of the mean value under simulated water wave. The findings provide valuable insights for advancing nanogenerator applications in real oceans.

The integration of high-density friction layer units is a promising approach for achieving high output in triboelectric nanogenerators (TENGs). Yet, the synchronization and sufficient contact separation of these high-density layer units are inherently challenging due to the cumulative impact of gravity. Herein, a tensegrity structure was applied and effectively organized the high-density stacked TENG units into an ordered whole, thereby proposing the T-TENG. Along with achieving orderly contact and separation of high-density friction layers, the T-TENG effectively reduced the device's height (up to 52%) and improved the friction layer surface area density (up to 1.07 cm−1). Significantly, the built-in prestress modulation not only enhances the device's load-bearing capacity but also enables ease in changing the T-TENG's response frequency by adjusting the prestress value. This is especially suitable for efficiently capturing omnidirectional wave energy in all-sea areas with frequency variations. The working mechanism and output influencing parameters of T-TENG were systematically expounded, and it demonstrated a maximum output voltage of up to 1020 V and output charge per unit time of 0.816 mC/min, sufficient to light up to 1512 LEDs directly. Moreover, customization of low-loss gas discharge tubes to amplify outputs allows T-TENG to harvest wave energy for power supply to small electronic devices such as water quality testing pens and Bluetooth modules when placed over water bodies. This work provides a foundational model to develop high-density friction layers and high-output TENGs.

In human-machine interaction, robotic hands are expected to work like human's hands and to be even more powerful or delicate in certain situations. To operate robotic hands via human gesture instead of handle or button will make this human-robot interface more natural and precise. Here, we designed a joint motion triboelectric quantization sensor (jmTQS) for constructing a robotic hand synchronous control system. Based on the ultrahigh sensitivity of a triboelectric nanogenerator (TENG) to mechanical displacement, the jmTQS designed as grating-sliding mode realized directly quantifying a joint's flexion-extension degree/speed. Through counting the pulses induced by jmTQS and signing the positive/negative of the pulses to represent flexion/extension, the joint's angular position can be determined with absolute value on the basis of the initial human-robotic synchronizing position value. In the whole operating course, the intuitionistic human-robotic hand two-dimensional motion mapping can be preserved. The minimum resolution angle of the fabricated jmTQSs is 3.8° and can be further improved by decreasing the grating width. This direct quantization and intuitionistic mapping at the sensing stage greatly simplified the signal processing and classification algorithms, which contributes to achieving the natural, high-precision and real-time interface.

Collecting mechanical energy in the surrounding environment to power small electronic devices is an ideal method as a green and clean power source. Based on the working mechanism and the advantages of triboelectric nanogenerator (TENG), a robust rolling friction contact-separation mode TENG (CS-TENG) has been fabricated for harvesting vertical rotation energy by utilizing the integrated cylindrical surface with the conjunction of rolling contact electrification and electrostatic induction. The output current of the CS-TENG can maintain 96% (origin: 1.72 μA, final: 1.66 μA) after two days continuous work a rotation speed of 300 r/min. Furthermore, an electromagnetic and triboelectric hybrid contact-separation mode nanogenerator (HCS-TENG) has been further designed by coupling magnets in the rolling cylinders with copper coils as an electromagnetic generator (EMG) in the acrylic cylinder to implement the multi-functional properties. The gear transmission structure makes the device more facile to be installed on the rotation objects. The output performances of CS-TENG and EMG under various rotation speeds were systematically studied. It shows that the CS-TENG with six units can deliver an output power of 0.15 mW/cm2and the 100 μF capacitor can be charged to 6 V in less than 1 min by the hybridized nanogenerator at a rotating rate of 700 r/min. In addition, utilizing the output signal's intrinsic characteristics of CS-TENG, a self-powered rotation speed and displacement sensor using the dual cylinder structure TENG has been achieved for these rotating mobile devices that are inconvenient to get an additional power supply in the grimmest circumstances such as moon car or other celestial and tough environment detection equipment. This multifunctional TENG device reveals a significantly potential application in the grimmest circumstances as power source, self-powered electronics and sensor systems.

Ocean energy is one of the most promising clean and renewable natural energy sources, however, owing to traditional energy harvesting technology, the collection and utilization of ocean energy is extremely limited. In this work, a hybridized ocean wave nanogenerator (How-NG) based on honeycomb-like three electrodes has been proposed, which consists of a triboelectric nanogenerator (TENG) and an electromagnetic generator (EMG), where the TENG works in both in-plane sliding mode and vertical contact-separation mode. With innovative design in electrode structure and hybrid of TENG and EMG, the How-NG can harvest two types of wave energy, kinetic energy and potential energy of ocean surface wave. The honeycomb-like three electrode structure is designed to harvest wave energy in multi-angle range for random waves. In addition, by adjusting the weight of the magnet to achieve different resonance parameters, the How-NG could reach a resonant state and more efficient collection of ocean energy. Furthermore, the influence of the working frequency and sliding displacement on the electrical outputs of the TENG unit and EMG unit are investigated systematically. The maximum output energy of TENG and maximum power of EMG can reach 21.7 µJ and 8.23 µW respectively at fixed working frequency of 4.0 Hz and sliding displacement of 3.5 cm. In addition, those two basic units are assembled vertically into a sealed cylinder acrylic shell which is used to drive LEDs by harvesting the water wave energy. This work presents a novel and efficient approach toward large-scale blue energy harvesting from the ocean.

With lightweight, high energy conversion and low cost, the triboelectric nanogenerators (TENGs) have presented its tremendous potential as a portable sustainable power source to small-scale portable/wearable electronic device. However, the insufficient output power of TENG is a bottleneck for its practical applications. Here, we report an ultrahigh output power, a whirligig-inspired TENG (Wi-TENG) designed according to an antiqueue whirligig toy that is capable of converting low-frequency pulling motion into a high-frequency rotation. It shows that the rotor in the Wi-TENG achieves a maximum speed of 11,250 rpm. Ultrahigh charge transfer quantity of ~ 310 μC and output power of 40.18 mW are obtained by per pulling of Wi-TENG. Moreover, a maximum short-circuit current of 317 μA and a constant open-circuit voltage peak value of 153 V can be generated by the Wi-TENG, which can rapidly charge a commercial capacitance (100 μF) to ~14 V within 10 s. After power management, this Wi-TENG is successfully demonstrated as a portable sustainable power source for driving a commercial blood glucose meter or a temperature-humidity sensor. This study presents the potential of Wi-TENG as a reliable portable instant power supply for personal health monitoring devices.

In order to solve the hysteretic character of the piezoelectric material for application, the initial weight factors of the hysteretic units are calculated by the Preisach theory and the first-order reversal curves test data, a hysteretic Preisach model based on the improved fuzzy least square support vector machine (improved FLS-SVM) is established. In the established model, the fuzzy least square support vector machine is introduced to calculate more weight factors of the hysteretic units and the adaptive variable chaos immune algorithm is introduced to optimize the penalty factor and the kernel parameter of the FLS-SVM (the penalty factor c= 35 and the kernel parameter σ= 1.35 are obtained). Moreover, the quadratic polynomial interpolation method is used to eliminate the sawtooth phenomenon. The validity of established model reveals that fuzzy least square support vector machine method based on adaptive variable chaos immune algorithm (FLS-SVMAVCIA) is more accurate than FLS-SVM method according to application results of the real actuators (the absolute mean error of the FLS-SVMAVCIA model is less than 1 µm and its maximum error is less than 2 µm). As a result, the hysteretic phenomenon can be effectively eliminated by the hysteretic Preisach model based on the FLS-SVMAVCIA method.

The development of lightweight, superportable, and sustainable power sources has become an urgent need for most modern personal electronics. Here, we report a cut-paper-based self-charging power unit (PC-SCPU) that is capable of simultaneously harvesting and storing energy from body movement by combining a paper-based triboelectric nanogenerator (TENG) and a supercapacitor (SC), respectively. Utilizing the paper as the substrate with an assembled cut-paper architecture, an ultralight rhombic-shaped TENG is achieved with highly specific mass/volume charge output (82 nC g–1/75 nC cm–3) compared with the traditional acrylic-based TENG (5.7 nC g–1/5.8 nC cm–3), which can effectively charge the SC (∼1 mF) to ∼1 V in minutes. This wallet-contained PC-SCPU is then demonstrated as a sustainable power source for driving wearable and portable electronic devices such as a wireless remote control, electric watch, or temperature sensor. This study presents a potential paper-based portable SCPU for practical and medical applications.

Harvesting energies from surroundings to build up self-powered sensing systems is very useful in our daily life. In this work, we design a cylinder-like fully-packaged hybrid nanogenerator for harvesting vertical rotation energy in broad frequency band by utilizing a magnet rod as the trigger to drive contact-separation mode triboelectric nanogenerator (TENG), and by coupling magnet rod with copper coils to operate electromagnetic generator (EMG). The stator-free structure makes the device more facile to be installed on the rotation objects. The output performances of TENG and EMG under various rotation speeds are systematically studied and clearly demonstrated by installing the device on a balance car, which proves that TENG can be more effective for low-frequency (<2Hz) energy scavenging and indicates the durability of the device can be largely enhanced with this structure design. In addition, the hybridized device is applied for harvesting wheel rotation energy from a car to drive wireless sensors for monitoring temperature, humidity, speed or even tire pressure simultaneously. This work presents a new platform of hybrid generators for harvesting rotation energy in broad frequency band and building up self-powered wireless sensing systems.

Liquid and gas flow sensors are important components of the micro total analysis systems (μTAS) for modern analytical sciences. In this paper, we proposed a self-powered triboelectric microfluidic sensor (TMS) by utilizing the signals produced from the droplet/bubble viathe capillary and the triboelectrification effects on the liquid/solid interface for real-time liquid and gas flow detection. By alternating capillary with different diameters, the sensor’s detecting range and sensitivity can be adjusted. Both the relationship between the droplet/bubble and capillary size, and the output signal of the sensor are systematically studied. By demonstrating the monitoring of the transfusion process for a patient and the gas flow produced from an injector, it shows that TMS has a great potential in building a self-powered micro total analysis system.

In the coming era of intelligence, the textile-based triboelectric nanogenerator (T-TENG) is considered to be one of the most important development directions to achieve flexible wearable sensing and micro/nano energy harvesting. Among them, due to excellent physical proeprties of nano/micro fibrous structure, fluff/terry /fleece/brush/fur/pile/villus/velvet structure fabrics are gradually being applied to TENG. However, the research on the relationship between the triboelectric properties of TENG and the structural parameters of fluff, as well as the fabrication of large-scale fluff TENG are very lacking. Here, a 3D warp knitted terry fabric TENG (WKTF-TENG) is mass produced by a mature warp knitted technology. The triboelectric properties of contact-separation mode, lateral-sliding mode and single electrode mode are systematically investigated by changing the height and density of the pile loops of the fabric. This study demonstrates that terry fabric is an excellent triboelectric materials for it high output and good wear resistance, especially for ateral-sliding mode. The output of WKTF-TENG even increases with the increase of working cycles due to the more fluffy and uniform distribution of fibers on the surface of the fabric. What’s more, the triboelectric properties of terry fabrics also have a great relationship with the compression properties of the pile loops. As smart textile matertail, WKTF-TENG can be usde as self-powered motion monitoring sensor and energy harvesting device. The research on the output performance of WKTF-TENG through theoretical analysis and experimental testing may provides a promising direction for fluff fabric based TENG.

Triboelectric nanogenerator (TENG) has recently emerged as one of the most promising technologies for capturing low-frequency ocean energy. However, TENG has some disadvantages, such as low volumetric energy density, poor versatility, and poor anti-storm ability, limiting its commercialization. In this study, an O-ring-like TENG (O-TENG) for blue energy harvesting is introduced. This generator can be prepared by flexible splicing of fan-ring-shaped TENG blocks with different angles. The modular design of the O-TENG not only realizes omnidirectional wave energy harvesting but also regulates its response frequency spectrum based on the surroundings, thereby enhancing the energy capture efficiency of the TENG array. The effect of the configuration parameters of the oscillation frequency and swing amplitude was systematically investigated to optimize the output performance of the O-TENG, and a maximum transfer charge of 29.90 μC was obtained. Furthermore, the O-TENG exhibited almost the same charging efficiency even when placed upside-down, demonstrating its anti-storm ability against strong winds and wave interferences. Experimentally, O-TENG can efficiently capture wave energy on the wave pool and drive commercial RF modules to realize wireless signal transmission successfully. This work demonstrates that O-TENGs can capture wave energy and are a potential energy source for ocean monitoring systems, promoting the construction of the IoTs.

The novel elliptical cylindrical structure (EC) provided an excellent self-stability, high sensitivity in small agitations, and most importantly, a distinctive anti-overturning capability for the EC-triboelectric nanogenerator (EC-TENG).Benefitting from the fully symmetrical design, the EC-TENG could maintain the original output after being overturned under extreme conditions, distinguishing itself from previous TENGs.Two built-in TENGs designed for use in rough seas and tranquil seas improved the collection efficiency for all-weather wave energy.

Understanding of the triboelectric charge accumulation from the view of materials plays a critical role in enhancing the output performance of triboelectric nanogenerator (TENG). In this paper, we have designed a feasible approach to modify the tribo-material of TENG by filling it with high permittivity nanoparticles and forming pores. The influence of dielectricity and porosity on the output performance is discussed experimentally and theoretically, which indicates that both the surface charge density and the charge transfer quantity have a close relationship with the relative permittivity and porosity of the tribo-material. A high output performance TENG based on a composite sponge PDMS film (CS-TENG) is fabricated by optimizing both the dielectric properties and the porosity of the tribo-material. With the combination of the enhancement of permittivity and production of pores in the PDMS film, the charge density of ∼19 nC cm–2, open-circuit voltage of 338 V, and power density of 6.47 W m–2are obtained at working frequency of 2.5 Hz with the optimized film consisting of 10% SrTiO3nanoparticles (∼100 nm in size) and 15% pores in volume, which gives over 5-fold power enhancement compared with the nanogenerator based on the pure PDMS film. This work gives a better understanding of the triboelectricity produced by the TENG from the view of materials and provides a new and effective way to enhance the performance of TENG from the material itself, not just its surface modification.

A folded elastic strip-based triboelectric nanogenerator (FS-TENG) made from two folded double-layer elastic strips of Al/PET and PTFE/PET can achieve multiple functions by low frequency mechanical motion. A single FS-TENG with strip width of 3 cm and length of 27 cm can generate a maximum output current, open-circuit voltage, and peak power of 55 μA, 840 V, and 7.33 mW at deformation frequency of 4 Hz with amplitude of 2.5 cm, respectively. This FS-TENG can work as a weight sensor due to its good elasticity. An integrated generator assembled by four FS-TENGs (IFS-TENG) can harvest the energy of human motion like flapping hands and walking steps. In addition, the IFS-TENG combined with electromagnetically induced electricity can achieve a completely self-driven doorbell with flashing lights. Moreover, a box-like generator integrated by four IFS-TENGs inside can work in horizontal or random motion modes and can be improved to harvest energy in all directions. This work promotes the research of completely self-driven systems and energy harvesting of human motion for applications in our daily life.

A planar spiral-like electrodes (PSE) based triboelectric generator has been designed for harvesting rotary mechanical energy to translate into electricity. The performance of the PSE-triboelectric generator with different cycles of spiral-like electrode strip at different rotating speeds is investigated, which demonstrates the open-circuit voltage and short-circuit current of 470 V and 9.0 μA at rotating speed of 500 r/min with three cycles. In addition, a novel coaxially integrated multilayered PSE-triboelectric generator is built, which can enhance the output of the power effectively. The short-circuit current, the open-circuit voltage, and output power reach to 41.55 μA, 500 V, and 11.73 mW, respectively, at rotating speed of 700 r/min. The output power of the multilayered PSE-triboelectric generator can drive 200 LEDs connected in antiparallel and charge a 110 μF commercial capacitor to 6 V in 23 s. Besides, due to the spiral-like electrode structure, the PSE-generator can work simultaneously in the modes of triboelectricity and electromagnetic induced electricity by sticking a small magnet on the rotating disk. The electromagnetic induced output power reaches to 21 μW at a loading resistance of 2 Ω at a rotating rate of 200 r/min. The spiral-like electrode structure not only broadens the electrode structure design but also adds a new function to the electrode.

A novel honeycomb-like triboelectric generator (HTEG) based on three electrodes has been designed for harvesting mechanical energy in full space. It has symmetric and periodic arrangement of the three electrodes in plane or on the inner surface of ball, which can harvest sliding energy along arbitrary direction without off state because each electrode is always surrounded by the electrodes different from itself. Meanwhile, the device can effectively scavenge ambient vibration energy as an independent generator in full space by working at both contact-separation mode and sliding mode without contacting with the ground. The maximum output current density, voltage and power density can reach 16.4mA/m2, 413V, and 2.1W/m2, respectively, by working in plane sliding mode, and the maximum output current to be 0.55μA by working in sliding mode on an inner surface of a spherical shell. The HTEG can charge a 100μF commercial capacitor to 2.1V in 80s. The football-like HTEG is used as a vibration alertor, which could be applied in vibration monitor or geologic hazard alertor for bridges and buildings. The idea of multi-electrode in HTEGs would be an effective strategy to achieve multi-function in scavenging energy.

The annual energy consumption to supply traditional power for cooling or heating applications is tremendous. Refrigeration or heating technology that does not rely on traditional energy sources is of great interest for modern society to achieve energy conservation and emission reductions. In this work, we demonstrated a self-powered cooling and heating system, consisting of a triboelectric nanogenerator (TENG), a power and charging management module, and an electrocaloric (EC) material. Ferroelectric ceramics of 0.1 PbTiO3–0.9 PbSc0.5Ta0.5O3(PSTT) with high EC at room temperature were successfully prepared. By converting the TENG-harvested kinetic energy of the mechanical motion into electrical energy and applying or releasing a polarized electric field to 12 PSTT sheets through circuit management, we achieved excellent dual self-powered cooling/heating functions in the room-temperature range. When the operating frequency of the TENG was 3 Hz, in a space with a specific surface area ratio of only 3.328 % and a volume ratio of 0.433 %, a temperature change of 0.5 K was achieved within 5.5 min, and the energy conversion efficiency reached 10.926 %. Because the TENG can effectively harvest the kinetic energy of various motions, including body motions and widely distributed wind, water wave, and raindrop energy in nature, it can be used to develop compact, miniaturized, and self-powered solid-state cooling/heating devices based on the EC effect. With the advantages of a high coefficient of performance, ease of use, zero emissions and lack of pollution production, our proposed approach is expected to achieve widespread application in various fields.

Great attention has been paid to nanogenerators that harvest energy from ambient environments lately. In order to give considerable output current, most nanogenerators require high-velocity motion that in most cases can hardly be provided in our daily life. Here we report a notepad-like triboelectric generator (NTEG), which uses simple notepad-like structure to generate elastic deformation so as to turn a low-velocity kinetic energy into high-velocity kinetic energy through the conversion of elastic potential energy. Therefore, the NTEG can achieve high current output under low-velocity motion, which completely distinguishes it from tribogenerators previously reported. The factors that may affect the output performance are explored, including the number of slices, active length of slice, press speed, and vertical displacement. In addition, the working mechanism is systematically studied, indicating that the efficiency of the generator can be greatly enhanced by interconversion between kinetic energy and elastic potential energy. The short-circuit current, the open-circuit voltage, and power density are 205 μA and 470 V and 9.86 W/m2, respectively, which is powerful enough to light up hundreds of light-emitting diodes (LEDs) and charge a commercial capacitor. Besides, NTEGs have been successfully applied to a self-powered door monitor.

Obtaining inspirations from natural selection have promoted wearable electronics innovation and provided a broad prospect for smart textiles compatible with excellent biological characteristics. Combining bionic scales with knitted structure can satisfy the conflicting requirements of protection and flexibility, which is vital to the smart outdoor garment application. However, it is very difficult to integrate high-speed fabrication and intelligentization of the complex bionic structure and the fabric while maintaining the original flexibility, comfort, and breathability of the fabric as much as possible. Herein, a novel, one-time, high-speed V-bed flat knitting fully-formed technology is used to prepare a bionic scales knitting triboelectric generator (BSK-TENG) as a new kind of wearable fabric with both intelligence and function. When used outdoors, the BSK-TENG can harvest water-drop energy and biomechanical energy owing to its distinctive 3D hierarchy structure. Besides, a multifunctional and intelligent personal outdoor rescue system with wireless signal transmission is also designed and manufactured by using the BSK-TENG as a self-powered and wearable human-computer interaction sensing device. What’s more, due to the obvious anisotropy exhibited during bending, the BSK-TENG can be further used as joint supporting protection for outdoor sports. This mass-produced 3D BSK-TENG not only has great commercial potential, but also can provide a promising research direction for multifunctional wearable devices in energy harvesting, self-powered sensing and human health protection.

Gasolines of two different octane numbers are experimentally distinguished using a thin metal sheet perforated with a periodic hole array terahertz surface plasmon (SP) sensor. This sensor is proved to be very sensitive to the change in permittivities of analytes. The differences between the gasolines 93# and 97# in composition lead to various refractive indices, permittivities, and absorption coefficients, thus varying their interactions with surface waves on the sensor, which enables a distinction of 6 GHz between the two octane numbers in the transmission peaks. The freestanding SP sensor is effective and reliable and can be simply employed in analyte distinction, which has potential applications in the petroleum industry.

The effect of a dielectric overlayer on terahertz transmission through a freestanding metallic array of subwavelength holes is experimentally presented. There is a remarkable resonance redshift from 0.600 to 0.498 THz at the surface plasmon (SP) metal–dielectric resonance mode with increasing film thickness. When the overlayer film is thicker than a critical thickness, the resonance frequency becomes steady at the final resonance frequency ω_f. On the basis of the dispersion relation of SPs, two kinds of glutamic acid enantiomers are distinguished by use of SP-enhanced terahertz spectra of metallic array of subwavelength holes according to the result of ω_f. The terahertz plasmonic hole array with the sensitive nature provides an approach to distinguish trace amount of powder substances, which has a promising application prospect in the fields of public security and biomedical science, such as distinguishing between isomers and identifying expensive medicines and drugs.

Abstract: About 80% of all urological stones are calcium oxalate, mainly caused by idiopathic hyperoxaluria (IH). The increased absorption of oxalate from the intestine is the major factor underlying IH. The continuous self-renewal of the intestinal epithelium is due to the vigorous proliferation and differentiation of intestinal stem cells. If the intestinal stem cell population can acquire the ability to metabolize calcium oxalate by means of oxc and frc transgenes, this will prove a promising new therapy option for IH. In our research, the oxalate-degrading genes of Oxalobacter formigenes (Oxf)—the frc gene and oxc gene—were cloned and transfected into a cultured mouse-derived intestinal SC population to give the latter an oxalate-degrading function. Oxf was isolated and cultivated and the oxalate-degrading genes—frc and oxc—were cloned. The dicistronic eukaryotic expression vector pIRES-oxc-frc was constructed and transferred into the mouse stem cell population. After selection with G418, the expression of the genes was identified. The oxalate-degrading function of transfected cells was determined by transfection into the intestinal stem cell population of the mouse. The change in oxalate concentration was determined with an ion chromatograph. The recombinant plasmid containing oxc and frc genes was transfected into the stem cell population of the mouse and the expression of the genes found normal. The cell population had acquired an oxalate-degrading function. The oxc and frc genes could be transfected into the intestinal stem cell population of the mouse and the cells acquired an oxalate-degrading function.

Triboelectric nanogenerators (TENGs) have recently become some of the most promising harvesters of the immense energy stored in the constant motion of ocean waves. Since ocean waves are chaotic and irregular, a TENG suitable for multiple motions is highly desirable for blue energy harvesting. We designed and fabricated a flower-like TENG (FL-TENG) for kinetic energy harvesting with six degrees of freedom. It consisted of six flower-petal sub-TENGs and two flower-core sub-TENGs that worked in the contact-separation mode. The FL-TENG converted kinetic energy into electric energy with the “flowering” and “folding” motions triggered by water waves. The petals of the FL-TENG mainly collected kinetic energy with two degrees of freedom for horizontal motion and with three degrees of freedom for rotational motion, and the cores of the TENGs harvested translational kinetic energy with one degree of freedom in the vertical direction. The FL-TENG demonstrated excellent power generation performance for different motion triggers. In various water wave environments, the FL-TENG efficiently collected kinetic energies with different degrees of freedom. Triggered by a water wave frequency of about 1.3 Hz and a wave height near 8 cm, the FL-TENG charged a capacitor of 220 μF to a voltage of 1.3 V in 1 min, supplying power to a watch, a calculator, and a hygrometer. It had robust functionality efficiency for various waves and it showed promising applications in developing self-powered smart marine sensors and distributed power systems in oceans.

The triboelectric nanogenerator (TENG) is a promising technology for harvesting low-frequency ocean energy, while a low surface charge density sets back its industrialization. Normally, owing to insufficient friction the traditional contact-separation mode has difficulty achieving a high surface charge density as that of sliding friction mode, which also can hardly maintain long-term sustenance due to abrasion. Herein, we designed a synchronous contact-separation triboelectric nanogenerator (SC-TENG) with intermittent sliding friction self-excitation that can achieve the dual functions of long-term sustenance of a high surface charge density and low friction-induced loss. A movable pendulum structure rotates intermittently to replenish the charge for its own, thus sustaining a high surface charge density for continuous contact-separation working mode. Several comparative experiments are conducted, showing short-time sliding friction made it easier to improve the surface charge density and output performance than long-term contact-separation friction. The single TENG with short-term friction increases by seven-fold in the transferred charges, 3.2 times in output current, compared to the TENG without friction. The SC-TENG could generate a high voltage of 1284V and maximum peak power of 8.3mW at 1Hz. With those capacities, the TENG can easily capture the water wave energy to power a commercial thermohygrometer and portable wearable device. SC-TENG proposes an innovative design and a new strategy for preparing the TENG with high output and low loss.

By counting the positive/negative pulses in unit time to sense the degree, speed, and direction of finger motion in real-time.The magnetic array assisted sliding structure translates sliding motion into contact-separation thus improves the durability and low-speed signal amplitude.The magnetic track constrains the sliding direction that greatly improves the stability.

Touch pad is an important human-machine interface in many information exchange scenarios. The rapid develop of portable or wearable devices and internet of things calls for a self-powered, thin, flexible, efficient and secure tactile mapping solution. Here, we present a triboelectric 3D touch pad with the above advantages. It consists of a multi-channel positioning layer and a single-channel pressure sensing layer both based on the rational design of triboelectric nanogenerator. Specially, the positioning layer is developed as a XY Complementary Subdivision Pattern (XYCSP) to reduce the number of channels as well as the XY crosstalk. With this particular pattern, the near end crosstalk is suppressed to a value of 0.16 without additional shielding. Moreover, it can effectively respond to a contactor with big or small size by regulating successive subdivision of a positioning unit. Based on this optimal design, a trajectory imaging pad and an anti-peek built-in code lock are demonstrated, which has promising potential in universal tactile sensing for motion monitoring, electronic skin, robotics, and human-machine interactions.

Triboelectric nanogenerators (TENGs), a prospective technology for large-scale harvesting of blue energy from the ocean, have been extensively investigated recently. However, little attention has been paid to the cables linking the individual TENG units to form an energy harvesting network. Herein, several basic requirements for power cables suitable for effective TENG networks are outlined. The cables should avoid tangling among the TENG units, protect the transmission wires, and output electric power. Here, a TENG network based on plane-like power cables consisting of spring steel tapes and three polymer films is described. The steel tape inside the power cables has a dual role as both structural skeleton and an electrode. The tape guarantees the stability of the TENG network and eliminates the electrostatic induction from ions in seawater. The porous PTFE film on the outside is highly hydrophobic and generates electricity by liquid-solid interface contact while collaborating with the steel tapes. The working mechanism and output performance of the power cable were systematically studied. A maximum open-circuit voltage of 34 V and a transferred charge quantity of 25 nC were achieved using a single cable in a single period. An over-water test was also carried out to experimentally demonstrate the feasibility of the TENG networks. This work provides a possible strategy for network construction for large-scale blue energy harvesting.