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As a new generation of energy technology, triboelectric nanogenerators (TENGs) show increasing significance as clean power suppliers in helping fulfill the global carbon neutrality target. However, a major limitation is that the energy utilization efficiency of TENGs is extremely low due to mismatched convertors. Herein, we demonstrate a universal design procedure of matched inductors for effective electrostatic energy conversion. In addition, we also propose an optimum constant current resistance range to assess the constant load performance of energy management. By combining with a spark switch, energy management with 6 kV ultrahigh voltage was established, realizing a module energy conversion efficiency of 90.7%, a constant energy efficiency of 81.6%, a super-wide output voltage of 0–5 kV and a large optimum constant current resistance range. Moreover, sixteen parallel thermo-hygrometers can be constantly powered and a perfect stability of 97% was demonstrated. This general matched inductor design can greatly enrich the application ecology of TENGs.

In this work, we fabricated triboelectric nanogenerators (TENGs) with the triboelectric friction layer made of the organic semiconductor copper phthalocyanine (CuPc). Iodine was incorporated into CuPc to tune the work function of the CuPc films. With 10 wt% iodine doping concentration, the TENG showed an excellent output performance with a voltage output of 300 V, a current density of 110 mA m-2, and a power density of 8.68 W m-2 compared to those reported for inorganic semiconductor-based TENGs. Leveraging the ethanol sensitivity of CuPc, a self-powered ethanol sensor was also demonstrated. The successful demonstration of organic semiconductors as the triboelectric friction layer will enable the development of fully flexible high performance semiconductor-based TENGs, as well as direct current TENGs based on semiconducting heterojunctions.

Meeting the ever-increasing demand for portable, sustainable, and renewable nanogenerators that can convert mechanical energy into electricity is a key research issue. Therefore, to compensate for deficiencies in piezoelectric nanogenerators (PENGs) and triboelectric nanogenerators (TENGs), an efficient energy-harvesting hybrid tribo/piezoelectric nanogenerator (HTPENG) with an innovative structure of “microspheres@nanofibers” was developed to drive miniaturized portable electronic devices. Owing to its unique structure, the as-fabricated HTPENG manifested excellent electrical output properties. The short-circuit current, the open-circuit voltage and the power density of the HTPENG were 8.066 μA, 35.693 V, and 525.12 mW m−2, respectively, which are enough to light up a light-emitting diode in 20 seconds. It is expected that this research can provide new methods to enhance the electrical output properties of nanogenerators and stimulate new ideas for the structural design of nanogenerators in the future.

Based on the contact electrification and electrostatic induction, triboelectric nanogenerators (TENGs) can convert the ambient mechanical energy into an electrical one. Having a role as both an energy storage and an output device, the enhancement of the TENG performance can be achieved by increasing their capacitance. Since the capacitance of tribo-materials can be engineered by their thickness and dielectric constant, we attempted to produce porous polydimethylsiloxane (PDMS) composites with Au nanoparticles (NPs) to engineer the capacitance. To this end, PDMS elastomers with various pore sizes were produced using sugar particles with a range of grain sizes. Then, the hydrophobic surface of PDMS elastomer was coated with polydopamine (PDA) to promote the homogeneous deposition of hydrophilic Au NPs on the PDMS surface. By using PDMS/PDA/Au composites, here we show the importance of pore size in adjusting the capacitance of the tribo-material. In particular, decoration of the PDMS surface with Au NPs engineered the dielectric constant of PDMS/PDA/Au composites, while the introduction of pores reduced the thickness of the composites under external pressure. Consequently, PDMS/PDA/Au composites exhibited enhanced TENG performance in a pore-size dependent manner.

Summary Electrostatic charges are easily generated on surfaces during contact electrification. Although these invisible charges have emerged as a new dimension in mediating the functions of surfaces, such as energy conversion, liquid transport, reactivity, and adsorbability, the accumulation of charges on surfaces can also pose many undesirable consequences. Despite notable progress, existing approaches in engineering antistatic surfaces suffer from limitations such as the need to modify bulk materials or for delicate control of patterning on surfaces that rely on the neutralization of generated charges. Herein, we report a general toolbox for designing antistatic coatings by leveraging on chemically heterogeneous components with electron-donating and electron-accepting functions, i.e., N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and 1H,1H,2H,2H-perfluorooctyl trimethoxysilane, to molecularly engineer the surface potential to achieve an electrostatic homogeneity and completely prevent charge generation. Our approach is general, which allows the facile fabrication of antistatic coatings on various materials, even flexible and curved, with good re-writability and transparency.

An additive-free β-phase porous poly(vinylidene fluoride) (PVDF) aerogel with high electron affinity was successfully prepared through a simple solvent exchange method. The as-prepared additive-free PVDF aerogel shows high output performance when used as a triboelectric layer in a triboelectric nanogenerator (TENG). High output performance with an open-circuit voltage (Voc) of 90 V and a short-circuit current (Isc) of 15 μA are obtained under a periodic stress of 16 N (0.08 MPa) at a frequency of 10 Hz, and the calculated power density is 6.15 W m−2, which represents an 8.2-fold enhancement compared to TENGs based on non-aerogel PVDF. The TENG based on the β-phase PVDF aerogel can light up 30 blue LEDs. Furthermore, the prepared TENG can also be used as a self-powered motion sensor with high sensitivity. The non-crosslinked PVDF aerogel has the potential to be used for high-performance TENG and self-powered sensing applications. This research provides preliminary insights into the application of porous non-crosslinked polymer aerogels in the field of energy harvesting.

Triboelectric nanogenerators (TENGs) that convert mechanical energy into electricity have been considered as an economical strategy for energy harvesting. Modification of the surface properties of triboelectric materials is a straightforward method to improve the performance of TENGs. In this study, for the first time, we demonstrate a promising strategy to improve the performance and stability of TENGs by using electrostatically self-assembled 1H,1H-perfluorooctylamine (F15-NH2) as the surface modification layer for the polydimethylsiloxane (PDMS) dielectric layer. Our results indicate that the protonated amine groups present on F15-NH2 can anchor onto the PDMS surface via electrostatic interactions, whereas adoption of a slow-drying procedure during film formation enables highly electronegative perfluoroalkyl chains to accumulate at the air interface, facilitating the formation of an ordered molecular arrangement that can induce a favourable surface dipole for efficient electron transfer between the electrode and the dielectric layer. Importantly, this strategy can be applicable to a large-area plastic-based TENG, and a remarkable power density up to 57.1 W m−2 is achieved. To the best of our knowledge, the power density reported herein represents the highest value ever reported for solution-based chemically modified TENGs. The impressive output characteristics of the TENG enable 338 light-emitting diodes to be lit up instantaneously. More encouragingly, excellent durability of the TENG is attained when using a perylene diimide derivative-modified Ag layer as the electrode, exhibiting an almost unchanged Voc over 240 000 operation cycles. Our findings highlight the importance of surface engineering via electrostatically self-assembled materials for realizing high-performance and stable TENGs with high reproducibility. The strategies demonstrated herein enable the mass production of surface modification layers through processes that are compatible with scalable roll-to-roll manufacturing techniques, which can accelerate the commercialization of low-cost printed TENG technology.

Chemical sensors allow for continuous detection and analysis of underexplored molecules in the human body and the surroundings and have promising applications in human healthcare and environmental protection. With the increasing number of chemical sensors and their wide-range distribution, developing a continuous, sustainable, and pervasive power supply is vitally important but an unmet scientific challenge to perform chemical sensing. Self-powered chemical sensing via triboelectric nanogenerators (TENGs) could be a promising approach to this critical situation. TENGs can convert mechanical triggers from the surroundings into usable electrical signals for chemical sensing in a self-powered and environment-friendly manner. Moreover, their simple structure, low probability of failure, and wide choice of materials distinguish them from other chemical sensing technologies. This review article discusses the working principles of TENGs and their applications in chemical sensing with respect to the role of TENGs as either a self-powered sensor or a power source for existing chemical sensors. Advances in materials innovation and nanotechnology to optimize the chemical sensing performances are discussed and emphasized. Finally, the current challenges and future prospect of TENG enabled self-powered chemical sensing are discussed to promote interdisciplinary field development and revolutions.

Microfluidic technology, as a method for manipulating tiny fluids, has the advantages of low sample consumption, fast reaction, and no cross-contamination. In a microfluidic system, accurate manipulation of droplets is a crucial technology that has been widely investigated. In this work, a self-powered droplet manipulation system (SDMS) is proposed to realize various droplet operations, including moving, splitting, merging, mixing, transporting chemicals and reacting. The SDMS is mainly composed of a triboelectric nanogenerator (TENG), an electric brush, and a microfluidic device. The TENG serves as a high-voltage source to power the system. Using different electric brushes and microfluidic devices, different manipulations of droplets can be achieved. Moreover, by experiments and simulations, the influence of the electrode width, the electrode gap and the central angle of one electrode on the performance of SDMS is analyzed in detail. Firstly, by using electrowetting-on-dielectric (EWOD) technology, SDMS can accurately control droplets for long-distance linear movement and simultaneously control multiple droplets to move in a circular electrode track consisting of 40 electrodes. SDMS can also manipulate two droplets of different components to merge and react. In addition, using dielectrophoresis (DEP) technology, SDMS can separate droplets with maximum volumes of 400 μL and reduce the time of the complete mixing of two droplets with different components by 6.3 times compared with the passive mixing method. Finally, the demonstration shows that a droplet can be manipulated by hand power for chemical delivery and chemical reactions on a circular electrode track without an external power source, which proves the applicability of SDMS as an open-surface microfluidic device. Therefore, the self-powered droplet manipulation system proposed in this work may have great application in the fields of drug delivery, micro chemical reactions, and biological microanalysis.

Tribo-electric nanogenerator proved a better alternative energy resource for many electronic accessories because of its flexible nature and optimized device properties. It opens up the use of polymer materials (PMs) for harvesting mechanical energy. The disadvantage of the Tribo-Electric Nano Generator (TENG) is likely lower durability, limited short circuit output current, structural changes, post-stress conditions, etc. The purpose of this review article is more focused on systematic and detailed descriptions of TENGs. It gives an overview of tribo-electric polymer-based material formation and triboelectricity generation, structural modes of tribo-electric polymer-based nanogenerators, and its comparisons, measurement, and quantification of tribo-electric polymer-based nanogenerators based on structural and load conditions. Also, this article focused on TNEG efficiency enhancement techniques using various charge control circuit techniques. Possible applications of TNEG for various self-powered devices such as sensor, actuators and bio-harvesting utilities are discussed in detail.

In this study, we investigate triboelectrification in polymer-based nanocomposites using identical polymer matrixes containing different concentrations of nanoparticles (NPs). The triboelectric surface charge density on polymer layers increased as the difference in nanoparticle filler concentration between the two triboelectric layers escalated, despite the fact that the polymer matrix was the same in both layers. This effect was observed in tests of various polymer types and filler NPs. Our mechanical experiments and finite element analysis simulations confirmed that polymeric triboelectrification is related to the surface viscoelastic deformation that occurs during mechanical contact and separation, and is not dependent on electronic or chemical properties, but rather physicochemical and mechanical properties. This supports the heterolytic scission of covalent bonds in polymer chains as an explanation for the triboelectricity. Accordingly, this study marks a significant contribution to the fundamental understanding of the mechanism of polymeric triboelectrification and will be relevant to the development of triboelectric sensors and energy harvesters.

In this paper, we report on a new dielectric, a C60-containing block polyimide (PI-b-C60). This was realized by introducing C60 as pendent groups into a polymer backbone. When this dielectric was used in a non-contact mode triboelectric nanogenerator (TENG), it achieved high output power and reliable operation. Compared with perfluoroalkoxy alkane film-based TENGs, the TENG based on PI-b-C60 generated 4.3 times higher output power and a superior charge density of over 300 μC m−2 with a 3 times slower charge decay rate. These results are most likely due to the excellent charge-retention characteristics induced by the most negative electrostatic potential of C60 within the backbone, and these characteristics were confirmed by surface potential measurements. Furthermore, in the course of our work, two non-contact mode applications, a keyless electronic door lock system and a speed sensor with a tone wheel for a car, were developed. Without an ion injection process being needed, very sensitive and reliable operations of the speed sensor were successfully demonstrated, even under very humid conditions (∼99% RH).

Flexible and stretchable electrodes have been extensively explored in recent decades, promoting remarkable advances in wearable electronics. However, for the foreseeable future it will be hard to achieve a level of conductivity of stretchable electrodes equivalent to that of metallic electrodes, which undermines the potential for practical applications, especially for fiber-shaped electrodes with long length/diameter. Herein, the basic physical concept of the small resistance of parallel circuits was applied to a triboelectric nanogenerator (TENG) fiber/textile to dilute the negative effects of the huge resistance of stretchable electrode fibers. As a demonstration of the concept, stretchable gel electrode-based fibers were woven into parallel multi-fiber TENG structures (parallel-teng), which significantly reduced electrode resistance compared to single long-fiber knitting TENG (GS-teng). The output current of parallel-teng showed an 11.8 fold enhancement compared to that of GS-teng owing to the decrease in the inner resistance by an order of magnitude. This work demonstrates an easy method to reduce the electrode resistance using parallel multi-fiber structures, which provide an approach for dealing with low conductivity electrodes in practical application. Furthermore, other wearable devices where there is the challenge of stretchable high resistance of electrode fibers, such as fiber batteries and piezoelectric fibers, could be inspired by this work because of the versatility of the physical concept.

Triboelectric nanogenerators (TENGs) stand out from wearable energy-harvesting technologies due to their high output power and flexibility. Moreover, triboelectric materials particularly the electrodes are considered to be the most significant part, which directly affect the output, flexibility and the fabrication process. In this study, we propose the fabrication of a laser-induced graphene (LIG)-Au hybrid electrode-based flexible TENG by a simple laser-induced method. Utilizing multiple laser irradiation, the PI and metal precursor can be induced to form a porous Au-LIG hybrid electrode. The Au nanoparticles on porous LIG are uniform and dense. Furthermore, this simple method can control the concentration and pattern of the Au-LIG flexible electrode. Based on the Au-LIG flexible electrode, we fabricated a flexible TENG and investigated the effects of the Au concentration on the output performance. The maximum instantaneous power of the Au-LIG-based TENG increased about 4 times compared to that of the LIG-based TENG. Finally, we developed a TENG-based sensor for writing recognition. According to the voltage signal and signal order, we can refer the writing track. This cost-effective method can fabricate the flexible electrode with enhanced performance, which paves the development of flexible and wearable electronics.

Tuning Schottky barrier height is crucial to optimize the performance of Schottky junction devices. Here, we demonstrate that the Schottky barrier height can be tuned with the voltage from a triboelectric nanogenerator (TENG). Schottky barrier heights at both ends are increased after the treatment with the voltage generated by the TENG. The electric field generated by the impulse voltage of the TENG drives the diffusion of the ionized oxygen vacancy in a CuO nanowire, which induces the nonuniform distribution of the ionized oxygen vacancy. The positively charged oxygen vacancy accumulates at the contacted interface of Pt and the CuO nanowire, and it impels the conduction and valence bands to bend downwards. The Schottky barrier height is raised. A theoretical model based on the energy band diagram is proposed to explain this phenomenon. This method offers a simple and effective avenue to tune the Schottky barrier height. It opens up the possibility to develop a high-performance Schottky sensor by tuning the Schottky barrier height.

Harvesting mechanical energy from the surroundings can be a promising power source for micro/nano-devices. The triboelectric nanogenerator (TENG) works on the principle of triboelectrification and electrostatic induction. So far, metals and polymers have mostly dominated the conventional triboelectric series, but there is a need to find novel materials to extend the triboelectric series and further improve the performance of a TENG. Herein, a zeolitic imidazole framework (ZIF-67) was synthesized using a room temperature solvent-assisted route. Extensive material analysis was performed to understand its structural and chemical properties. Further, a simple vertical contact mode S-shaped TENG device (abbreviated further as S-TENG) was fabricated using an additive manufacturing approach. ZIF-67 acted as a positive triboelectric layer while Teflon/PDMS acted as a negative triboelectric layer. The multi-unit S-TENG device was further utilized for self-powered recognition of the various gaits using a digital signal processing approach. The S-TENG device based on ZIF-67 and Teflon produced a voltage of 118 V, a current of 1.7 μA, and a power density of 15 μW cm2 at a load resistance of 50 MΩ. The gait analysis of different volunteers was recorded by employing the S-TENG device and the digital signal processing route to effectively distinguish the gait patterns for the prevention of falls and injury. The S-TENG device was utilized to charge a commercial capacitor for powering a wristwatch and further it was attached to a robotic gripper for object identification.

Combining different devices to harvest energy is a novel strategy to increase the efficiency and applicability of devices that harvest mechanical energy. In the present work, we designed and fabricated a hybrid generator by combining piezoelectric, triboelectric, and electromagnetic (EM) effects to harvest mechanical vibrations. With the selection of ZnO–PVDF, a highly piezoelectric material as one of the contacting materials for the triboelectric effect allowed us to combine both the piezoelectric and triboelectric effects without the need to fabricate each unit individually. Because of the design of the device, the electricity from each effect was generated simultaneously. We achieved a maximum open-circuit output voltage of ∼192 V and a short-circuit current of ∼2.78 mA from the piezoelectric–triboelectric and EM hybrid device. The hybrid system was shown to be able to charge a 10 μF capacitor up to a voltage of 7.35 V in a short period of 170 s, an achievement not possible with the individual units. The maximum saturation voltage measured across the capacitor increased after combining the trio of effects, i.e., the piezoelectric, triboelectric, and EM effects, a feature that expands the applicability of the device to power instruments requiring higher voltages. The application potentials of the hybrid device in powering a digital calculator, screw gauge meter, and electrolysis of water to generate H2/O2 were demonstrated. The present work established a novel and practical approach to generate electricity from mechanical motions by combining piezoelectric–triboelectric and EM effects.

The demand of power supply for micro-devices results in the exploration of energy harvesting. A simple method was developed to construct hybrid energy harvester (HEH) consisting of piezoelectric energy harvester (PEH) and triboelectric energy harvester (TEH). The Mn-doped Ba(Ti,Sn)O3 (BTS) piezoelectric particles with an average size of 0.64 µm were used in the PEH unit. The polyimide with high electronegativity was used in the TEH unit. The P(VDF-CTFE)/BTS composite film exhibited a uniform distribution of BTS particles in P(VDF-CTFE) and a weak β-phase transformation. The open-circuit voltage and short-circuit current of the HEH were discussed at different BST content and external force. The HEH with 2 wt% BTS content shown an optimal output with 4.1 V and 2.5 µA. The HEH was sensitive to vertical stress, which can generate 12 V under a vertical force by fist. The HEH illustrated high stability after 800 cycles, which can obtain stable open-circuit voltage. This work provides a hybrid method of piezoelectric and triboelectric effects for energy-harvesting.

Numerous research fields adopting breathable, human-affinity, and biodegradable biopolymers for various applications have emerged. As one of the most common biopolymers due to its water-soluble and biodegradable properties, and being harmless to the human body, gelatin has a triple helix structure in its solid-state capable of forming a self-assembly. Here, the pore size (4 to 16 μm) of the gelatin/polyvinyl alcohol (PVA)/carbon (GPC) blend can be modified through the PVA content which is configurable to obtain different properties like air/light transmissivity, high conductivity with the blend of graphite and carbon black (40 to 50 S cm−1), with only carbon black (10 to 20 S cm−1), surface energy, and strain (5 to 11%) for several applications. In this study, a new secret tag application based on a GPC blend porous structure is presented for the first time. The optimized GPC aqueous solution may not only be coated directly on human skin to form an emotion sensor or breathable touchpad without causing irritation but could also be made into a multi-modal sensor for human activity with biodegradability. The GPC free-standing electrode film also yields a stable triboelectric output (75 V) when used as a triboelectric nanogenerator (TENG) by varying the surface area.

Moisture in the environment can severely decrease the contact charging properties of polymers, which usually reduce the output of solid–solid triboelectric nanogenerators (TENGs), hindering their further practical applications. To solve this problem, in this paper we fabricated a new type of polyethylene terephthalate (PET) based TENG, which can work stably in a high humidity environment with high output performance. The surface of the PET film is modified with β-cyclodextrin to introduce hydroxyl groups, which increase the ability to form hydrogen bonds with water molecules in a high humidity environment, immobilizing water molecules to participate in contact charging. Since water molecules are a more positive material, the PET film combined with water molecules will acquire more positive charges during the contact charging process, which will greatly increase the electrical output of PET-based TENGs. Different from the PET film-based TENG without hydroxyl on the surface, the electrical output of the β-cyclodextrin-modified PET-based TENG increases with the increase of environmental humidity. The circuit current (Isc) of the TENG increases from 3.7 μA to 16 μA when the humidity increases from 15% to 95%. Moreover, the dielectric properties of the PET film increase due to the introduction of amino groups in β-cyclodextrin, which causes the Isc of the TENG to increase by 3.7 times at 15% RH. This strategy highly expands the application scope of TENGs for energy harvesting and self-powered sensors in high humidity environments, especially in cloudy and foggy days or under water and sweat conditions.

Summary Energy harvesting plays an important role in developing power-independent electronics such as wearables, implantable devices, monitoring networks, and robotics. The triboelectric nanogenerator (TENG), a novel promising energy-harvesting technology, has attracted increasing attention across a broad range of applications from self-powered sensing to implantable medical devices to blue energy. However, a comprehensive review associated with the TENG-based hybrid energy system is lacking. Here, we systematically summarize the recent advances in the TENG-based hybrid energy-harvesting system with a focus on the concept designs and significant applications of the hybrid devices in various fields. The major hybridization designs through unique combinations of electromagnetic nanogenerators (NGs), piezoelectric NGs, solar cells, and thermo-/pyroelectric NGs with TENGs are discussed in detail for self-charging power units, self-powered biomedical systems, wearable electronics, environment-monitoring systems, and blue energy-harvesting facilities. We finally discuss the major challenges and perspectives for the future development of hybrid energy-harvesting systems.

A facile method to produce an MXene–TiO2 composite is demonstrated for enhanced field emission display applications. The field emission performance of two-dimensional free-standing and linear-shaped field emitters has been systematically investigated and enhanced electron emission behaviors (e.g. emission current, stability and emission patterns) are achieved by compositing MXene and TiO2 nanowires. The relationship between the emission current density, electric field and anode-cathode gap distance is studied and the emitters, especially the cross-section of the composite film, show good performance. The emission current from the cross-section of the composite film can reach 289 mA cm−2, which is the best result of the state of the art compared to single MXene and TiO2 nanowires. We have also reported a triboelectric nanogenerator powered by free-standing MXene–TiO2 composite emitters, implying the feasibility of the self-powering field emission devices and possibly enlarging the applications of cold emitters in various fields.

It is of great commercial prospect to apply triboelectric nanogenerators (TENGs) to harvest mechanical energy from contact and sliding motion between fingers and the touch screen surface. For this application, the triboelectric material is required to have not only strong electronegativity but also transparency, low adhesion and low friction. Among the existing transparent triboelectric materials, polydimethylsiloxane (PDMS) is so soft and adhesive that it is not suitable to be applied on touch screens, and polyethylene terephthalate (PET) has weak electronegativity. Therefore, a transparent fluorinated polyimide (PI) film with a light transmittance of 90% is synthesized, and its electrical performance, adhesive and tribological properties are studied in this study. The electrification performance of the fluorinated PI increased by 60–70% compared to that of Kapton. In addition, fluorination reduces the adhesion and friction coefficient of the film, thus reducing the touch resistance and improving its durability in triboelectrification. Finally, the transparent PI-based TENG attached on the cellphone screen can effectively harvest mechanical energy to charge the capacitor with a voltage increment of 0.18 V with every tap on the screen surface.

This work introduces, for the first time, the energy harvesting performance of conjugated microporous polymers (CMPs) as tribo-positive materials for triboelectric nanogenerators (TENGs). Various nano or submicron CMP particles (CMP-X) were prepared by the Sonogashira coupling of 1,3,5-triethynylbenzene with 1,4-diiodoarenes. Optimized CMP-X nanoparticles in a polyurethane (PU) matrix showed excellent triboelectrification performance, displaying peak-to-peak voltages of up to 411 V and a maximum power density of 0.80 mW cm−2. Moreover, an optimized 5.0% CMP-H@PU-based TENG could be utilized as a power source for the charging of an electrolytic capacitor and for the operation of 100 LEDs.

Highlights 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. Supplementary information The online version contains supplementary material at (doi:10.1007/s40820-020-00575-2)., In human-machine interaction, robotic hands are useful in many scenarios. To operate robotic hands via gestures instead of handles will greatly improve the convenience and intuition of human-machine interaction. Here, we present a magnetic array assisted sliding triboelectric sensor for achieving a real-time gesture interaction between a human hand and robotic hand. With a finger’s traction movement of flexion or extension, the sensor can induce positive/negative pulse signals. Through counting the pulses in unit time, the degree, speed, and direction of finger motion can be judged in real-time. The magnetic array plays an important role in generating the quantifiable pulses. The designed two parts of magnetic array can transform sliding motion into contact-separation and constrain the sliding pathway, respectively, thus improve the durability, low speed signal amplitude, and stability of the system. This direct quantization approach and optimization of wearable gesture sensor provide a new strategy for achieving a natural, intuitive, and real-time human-robotic interaction. Supplementary information The online version contains supplementary material at (doi:10.1007/s40820-020-00575-2).

Layered double hydroxides (LDHs) have been extensively investigated for various applications such as drug delivery, energy storage, catalysis, and luminescence. In this study, an eco-friendly ZnAl–CO3–LDH–poly(vinylidene fluoride) (ZnAl–LDH–PVDF) composite acting as a triboelectric dielectric material is described. The composite material can realize a high-performance, flexible, and transparent triboelectric nanogenerator (TENG). The strong interactions between ZnAl–LDH and PVDF facilitate the formation of a spontaneous polar β-PVDF phase and enhance the dielectric properties of composite films considerably. The output performance of ZnAl–LDH–PVDF composite-based TENGs with various amounts of ZnAl–LDH was investigated. 20 wt% ZnAl–LDH–PVDF TENG demonstrated an output voltage of ∼230.6 V, current density of ∼5.6 μA cm−2, and power density of 0.43 mW cm−2. The pressure- and humidity-dependent outputs of the device enable it to be an effective self-powered pressure and humidity sensor. As a pressure sensor, the device revealed an excellent pressure sensitivity of 13.07 V kPa−1. As a humidity sensor, it exhibited a response of 259.4% in the voltage detection mode. The improved polar β-PVDF phase and dielectric properties of the ZnAl–LDH–PVDF composite make it suitable for high-performance mechanical energy harvesters in self-powered sensor applications.

Acceleration sensors have a wide variety of applications for industrial engineering, biology and navigation. However, passive sensing, narrow detection range, large size, and high manufacturing cost curb their further development. Here, we present a miniaturized acceleration sensor (MAS) with rationally patterned electrodes, based on the single electrode triboelectric mechanism, featuring small size, high accuracy, large detection scale, and environmental friendliness. A stainless-steel ball, as the moving part of the MAS, experiences physical movement that is converted into an electrical signal. Equipped with rationally patterned electrodes, the MAS retains the smallest size and lowest weight compared with the currently reported self-powered acceleration sensors. Benefiting from the voltage-relationship-based direction detection mechanism, eight directions can be identified by one TENG module. Consequently, rotated 22.5° relatively, two TENG modules enable the MAS to detect 16 directions. Moreover, accelerations ranging from 0.1 m/s2 to 50 m/s2 can be identified according to the relationship of response time and accelerations in the horizontal direction. The relationship is obtained through the measurements of the sum of output voltages (VSOC) for the four bottom electrodes with varying accelerations. In addition, no distinct decrease of VSOC is observed after continuously operating for 2000 circles, presenting excellent robustness. Hence, this cost-effective and rationally patterned MAS reveals great potential for human machine interaction, VR/AR (virtual/augmented reality), sports training, and smart city.

Triboelectric nanogenerators (TENGs) have attracted many research endeavors as self-powered sensors for force, velocity, and gas detection based on solid-solid or solid-air interactions. Recently, triboelectrification at liquid-solid interfaces also showed intriguing capability in converting physical contacts into electricity. Here, we report a self-powered triboelectric sensor for liquid chemical sensing based on liquid-solid electrification. As a liquid droplet passed across the tribo-negative sensor surface, the induced surface charge balanced with the electrical double layer charge in the liquid droplet. The competition between the double layer charge and surface charge generated characteristic positive and negative voltage spikes, which may serve as a "binary feature" to identify the chemical compound. The sensor showed distinct sensitivity to three amino acids including glycine, lysine and phenylalanine as a function of their concentration. The versatile sensing ability was further demonstrated on several other inorganic and organic chemical compounds dissolved in DI water. This work demonstrated a promising sensing application based on the triboelectrification principle for biofluid sensor development.

In a thermal power plant, online measurement of the size distribution of pneumatically conveyed pulverized fuel is essential for the improvement of combustion efficiency and the reduction of pollutant emissions. In this article, an innovative instrumentation system based on acoustic emission (AE) detection and triboelectric sensing is proposed for the on-line continuous measurement of particle size distribution. With a waveguide protruding into the flow, the AE signal is generated from the impacts of particles with the waveguide. The peak voltage of the AE signal is related to the particle size and impact velocity. For the first time, two triboelectric sensor arrays each with three arc-shaped electrodes near to the waveguide are used to measure the impact velocity. Meanwhile, a novel particle sizing algorithm with Gaussian prediction is proposed to reduce the effect of overlapping impacts and environmental noise on the peak distribution. With the known impact velocity measured from the triboelectric sensor arrays and the modified peak distribution, the measurement of particle size distribution is achieved. Experimental tests were conducted on a gas–solids two-phase flow rig to assess the performance of the developed measurement system. Silica sands in three size ranges of 116–750, 61–395, and 10– $246~\mu \text{m}$ , respectively, were used as test particles. The experimental results demonstrate that Spearman’s rank correlation coefficients between the measured and reference size distributions for all test particles are all greater than 0.8, while the discrepancy for each particle size segment is within ±4.8%.

The next-generation multifunctional soft electronic devices require the development of energy devices possessing comparable functions. In this work, an ultra-stretchable and healable hydrogel-based triboelectric nanogenerator (TENG) is prepared for mechanical energy harvesting and self-powered sensing. An ionic conductive hydrogel was developed with graphene oxide and Laponite. as the physical cross-linking points, exhibiting high stretchability (∼1356%) and healable capability. When using the hydrogel as the electrode, the TENG can operate normally at 900% tensile strain, while the electrical output of the TENG can fully recover to the initial value after healing the damage. This hydrogel-based TENG is demonstrated to power wearable electronics, and is used as a self-powered sensor for human motion monitoring and pressure sensing. Our work shows opportunities for multifunctional power sources and potential applications in wearable electronics.

The demand for energy is increasing tremendously with modernization of the technology and requires new sources of renewable energy. The triboelectric nanogenerators (TENG) are capable of harvesting ambient energy and converting it into electricity with the process of triboelectrification and electrostatic-induction. TENG can convert mechanical energy available in the form of vibrations, rotation, wind and human motions etc., into electrical energy there by developing a great scope for scavenging large scale energy. In this review paper, we have discussed various modes of operation of TENG along with the various factors contributing towards its efficiency and applications in wearable electronics.

The general purpose of the present article is to study the feasibility of removing brominated flame retardant (BFR) polymers from mixed granular wastes using triboelectric charging and electrostatic separation techniques. The study was carried out on mixtures consisting of equal quantities of plastic particles either BFR-free or containing 4.8% of hexabromobenzene (i.e., 40 000 ppm of bromine). Three triboelectric charging devices were used—a vibrating tribocharger [a container made of stainless steel, polystyrene (PS), or polypropylene (PP), and fixed on a vibrating table], a rotating cylinder tribocharger made of polyvinyl chloride, or a fluidized bed tribocharger, the walls of which were made of either poly methyl methacrylate, PS, PP, or polyethylene (PE). The experiments were carried out on three granular mixtures [BFR high impact PS (HIPS)/BFR-free HIPS, BFR PP/BFR-free PP, BFR PE/BFR-free PE]. The selective sorting of the granular mixtures was performed using a roll-type electrostatic separator. The results confirm that separating BFR plastics from BFR-free plastics is feasible. Best separation results were obtained for the mixtures tribocharged in the fluidized bed tribocharger.

Energy-harvesting textiles based on triboelectric nanogenerators (TENGs) have attracted intense attention, due to their broad potential applications in wearable electronics. However, the bottlenecks of limited and alternating current electrical output have greatly hindered the development of textile TENGs. Here, by simply and easily coating two electrodes on the top side (breakdown electrode) and bottom side (friction electrode) of a polyester–cotton fabric, a light-weight, highly flexible and wearable fabric-based direct current TENG (FDC-TENG) with high power output is developed. Various structural parameters and environmental factors are thoroughly and systematically explored for comprehensive understanding of the FDC-TENG. The surface charges induced by triboelectrification can be unidirectionally and efficiently harvested through the conductive plasma channel caused by air breakdown, which endows the finger-sized FDC-TENG with the abilities to light up 99 bulbs and 1053 LEDs and drive watches and calculators easily and directly without rectifying or capacitor charging. This work may provide a paradigm shift for high output direct-current power fabrics and expand their scope for application in wearable electronics.

The concept of piezoelectric nanogenerators (PENGs) and triboelectric nanogenerators (TENGs) as sustainable, clean, reliable and cost-efficient power sources has come a long way since their first discovery in 2006 and 2012 respectively. A significant amount of research has been conducted to improve the performance of nanogenerators for its successful implementation in Internet of Things, wearable electronics and self-powered systems. Here, this paper reviews the recent advancements in materials and their output parameters along with their specialties based on experimental and theoretical studies in the literatures. Basic working modes of the triboelectric nanogenerator are explained in detail and the general procedure to synthesize, measure and characterize a nanogenerator is introduced in a straightforward structure.

The advent of the internet of everything emanates the need of powering myriads of small-scale electronic gadgets and smart sensors using new renewable energy solutions. Triboelectric nanogenerators (TENGs) are emerging candidates to meet such requirements by scavenging mechanical energy from the surroundings. Here, we present a facile, scalable and robust TENG based on polyvinylidene difluoride (PVDF) and polymethyl methacrylate (PMMA) films without any complex fabrication steps. A spring assisted TENG (Sa-TENG) operating in contact separation mode has been designed, fabricated and demonstrated for harvesting mechanical energy associated with human activities such as finger tapping, palm tapping and heel tapping into useable electricity. With a moderate finger tapping force, the Sa-TENG has generated an open-circuit voltage of ∼120 V and a short circuit current density of ∼150 μA m−2. Also, it is shown that the electrical output of the Sa-TENG can be enhanced with an increase in input mechanical energy and the area of contact. The fabricated Sa-TENG has been used for powering electronics gadgets such as LCD clocks, digital thermometers, LEDs and seven-segment displays.

The application of low-powered, sustainable sensors to detect the leak of toxic gases in factories has gradually become a future trend. In our work, we proposed a NO2 gas sensor based on an In2O3/SnS2 composite powered by a high-stability triboelectric nanogenerator (TENG), where weighing paper and a polytetrafluoroethylene (PTFE) film were used as friction materials. The peak-to-peak voltage of the TENG can reach stable 600 V and the output power can up to 13 mW, which exhibits superior performance. The TENG can power small portable electronic devices such as 50 LEDs and calculators. The TENG is directly connected in series with a chemoresistive gas sensor to form a TENG-driven nitrogen dioxide sensor (TENS) for the spontaneous detection of the concentration of NO2. The sensor exhibits a high response (∼15) and rapid response/recovery time (45 s/147 s) towards 50 ppm NO2 at 43% RH and room temperature of 25 °C. Finally, a self-powered alarm system based on the TENS has been developed to monitor the concentration of NO2 in the surrounding environment. This work not only broadens the application field of the TENG as a self-powered gas sensor, but also meets the requirements of industrial IoT technology for miniaturized, low-powered, and maintainable sensors.

Due to the increasingly serious environmental pollution and the extreme shortage of energy resources, harvesting clean and sustainable random energy from the environment is a scientific, effective, and necessary solution in the coming intelligent era. Such random and disorder energy, like that from human motion and textile-related movement, can be obtained via textile-based triboelectric nanogenerators (TENGs). However, research related to textile-based TENGs with mature, high-efficiency, and economical manufacturing techniques is limited. Here, by using a high-speed ring spinning method, negative Poisson's ratio yarn (NPRY) with a composite structure is designed and fabricated as a variety of intelligent device. Based on the special negative Poisson's ratio effect, NPRY combined with TENG can be used as a foundation structure to form diverse flexible textile-based electronic devices, such as an energy harvesting fabric, a self-counting yoga elastic band, and a self-powered pre-alarm cable. At the same time, NPRY-TENGs with different structures and structural parameters are systematically investigated to optimize the output performance in this work. This special, low-cost, and highly efficient NPRY as a foundation structure material has promising applications in the manufacture of all kinds of textile-based TENGs and harvesting a lot of random energy from the environment, where the random energy can be used by other electronic devices or those textile-based TENGs themselves as self-powered sensors.

Here, we demonstrate a dynamic perovskite device capable of converting mechanical energy into direct current (DC) electrical energy, combining two concepts: carrier generation from the triboelectric effect and carrier separation through band energy level difference. By analyzing and comparing different perovskite (FAPbI3, MAPbI3, MAPbBr3, PEA2PbI4, etc.) and charge transport layer (CTL) materials (spiro-MeOTAD, PTAA, TiO2, SnO2, etc.), the key rules for determining DC output and performances are identified: (1) a suitable band alignment (band position and bandgap) between perovskite and CTL can separate the carrier transfer; (2) a large difference in work function between two layers leads to high electrical potential difference; and (3) a high carrier concentration can enhance the DC power-generating performances. Furthermore, it is found that the light illumination acts as a stimulus to current output to a large extent, which is due to the coupling effect from triboelectric and photovoltaic effects. This study provides a set of key rules to explain the mechanism and to further improve the performance of the dynamic perovskite/CTL heterojunction.

With the rapid development of triboelectric nanogenerators (TENGs), it is urgent to develop novel friction materials to expand the conventional materials in the triboelectric series to meet the diverse requirements of far-ranging applications. In this work, two α-Keggin-type polyoxometalate (POM)-based metal–organic hybrid compounds were synthesized through the fine-tuning of the reactants under the same reaction conditions, including one discrete ionic structure and one one-dimensional infinite chain structure. They were first used as triboelectric layers, together with polyvinylidene fluoride (PVDF) as the opposite layer to fabricate TENGs. The results displayed that the TENG based on the discrete hybrid with a higher permittivity displayed a superior output performance of 395 V and 34.8 μA and demonstrated good stability during cyclic measurement of over 50 000 cycles.

Pressure sensors have attracted much attention for their potential applications in health monitoring, wearable devices, electronic skins, smart robots, etc. With the rapid development of the Internet of Things, considering the large number and small scale of sensors, power consumption has become a key factor in large-scale applications. A new generation of self-powered pressure sensors based on a triboelectric nanogenerator has been developed in terms of its incomparable advantages in power consumption and potential performance. Based on the coupling effects of triboelectrification and electrostatic induction, it enables obtaining information on the mechanical input, e.g., magnitude and frequency, by analyzing the electrical output signals. Intensive efforts have been devoted to improving the sensing performance of triboelectric pressure sensors to meet the demands of practicality. In this review, the key advancements in materials, structures and applications of self-powered triboelectric pressure sensors are systematically reviewed. Then, the theoretical basis, impact mechanism and approaches to optimize the pressure sensing performance have been comprehensively analyzed. Finally, the future perspectives of self-powered triboelectric pressure sensors have also been discussed.

As an efficient power technology, a triboelectric nanogenerator (TENG) has made a huge impact on many research fields and exhibits exciting prospects in the future world. There are two output modes of the TENG, the alternating current (AC) mode based on the coupling of triboelectrification and electrostatic induction, and the direct current (DC) mode based on the coupling of triboelectrification and air-breakdown. AC can be converted into DC by rectification. However, from the symmetry argument, there should be an inverting mode to convert the DC into AC. Herein, an inverting TENG to realize the AC mode based on the coupling of triboelectrification and air-breakdown is proposed for the first time by setting alternating polarity distribution areas. Different from the fixed waveforms of a traditional AC-TENG, the inverting TENG exhibits such unique characteristics that both the width ratio and amplitude ratio of AC signals can be changed by tuning the distributed width and electronegativity difference of two opposite materials. This work paves the way for the development of a symmetry output mechanism for the TENG, from AC to DC, and from DC to AC, or even hybrid DC and AC in one TENG, and these powerful functions endow the inverting TENG with more advantages for future self-powered intelligent systems.

This work reports a new approach to amending polydimethylsiloxane (PDMS) by supporting α-Fe2O3 nanoparticles (NPs), thereby generating a material suitable for use as a negative triboelectric material. Additionally, human hair exhibits a profound triboelectrification effect and is a natural regenerative substance, and it was processed into a film to be used as a positive triboelectric material. Spatial distribution of α-Fe2O3 NPs, the special surface morphologies of a negative tribological layer containing nano-clefts with controlled sizes and a valley featuring a positive tribolayer based on human hair made it possible to demonstrate facile and scalable fabrication of a triboelectric nanogenerator (TENG) presenting enhanced performance; this nanogenerator produced a mean peak-to-peak voltage of 370.8 V and a mean output power density of 247.2 μW cm−2 in the vertical contact-separation mode. This study elucidates the fundamental charge transfer mechanism governing the triboelectrification efficiency and its use in harvesting electricity for the further development of powerful TENGs suitable for integration into wearable electronics and self-charging power cells, and the work also illustrates a recycling bioeconomy featuring systematic utilization of human hair waste as a regenerative resource for nature and society.

Polydimethylsiloxane (PDMS) nanocomposite (NC) macroporous films were prepared by a Pickering high internal phase emulsion (HIPE) templating technique and used as effective dielectrics for enhancing the performance of triboelectric-nanogenerators (TENGs). HIPEs were formulated using commercial PDMS and water as the continuous and dispersed phase, respectively. The formation and solidification of PDMS-based HIPEs were possible through stabilization with silver-nanoparticles (Ag-Nps) and surfactant (Span 20) mixtures. The resulting PDMS-NC-polyHIPE films presented an interconnected 3D macroporous structure with Ag-Nps on their porous surface. The addition of different amounts of Ag-Nps (0, 4, 20, 28, 36 wt%) in HIPE formulations allowed modification of the pore size, total pore volume and dielectric properties of the tribo-materials. Results revealed that both the porosity and dielectric properties of these materials play an important role in enhancing the output performance of TENGs. Thus, the best TENG based on the PDMS-NC-polyHIPE film was achieved with 20 wt% of Ag-Nps, with voltage, current and power values of 4.88 V, 0.433 μA and 2.1 μW, respectively, which gives over 3.28-fold power enhancement compared with the reference TENG (based on a PDMS film without porosity or Ag-Nps). Therefore, the preparation of tribo-materials through a Pickering HIPE templating technique provides a novel, effective and easy way for the improvement of the TENG's performance.

With the rapid development of technology in the modern era, the use of energy in different forms and levels has changed due to the numerous electronics devices and sensor systems utilized in society to ensure a smooth and comfortable digital life. In this journey, the use of low-power sensor devices is increasing dramatically due to the toxicity of batteries and conventional energy supply issues. Among the many solutions such as triboelectricity, piezoelectricity, thermoelectricity, and pyroelectricity, redox-induced electricity in energy scavenging and self-powered sensors is considerably appealing. This review presents a concise overview of the latest evolution in redox-based energy generation and the integration of redox-induced electricity generators with sensor devices including device performances. This review focuses on the current trends for energy solutions with alternative and sustainable energy resources such as human fluids, waste heat, thermogalvanic cells, and photoelectrochemistry, which are currently becoming research hotspots. Also, this review will provide a brief discussion about the performance enhancement techniques currently being investigated such as the modification of electrolytes, roles of redox couples, and concentration effects for a broader view to analyze the factors affecting the device output.

Recently, dynamic Schottky diode or p–n junction-based triboelectric nanogenerators (TENGs) which generate direct current were reported. However, most of them exhibited low output voltage because their semiconducting friction layers were directly constructed on an electrode. In this study, we report a “tribodiffusion-driven” TENG, the working mechanism of which differs from previously reported ones. When n-type MoS2 and p-type polypyrrole (PPy) are in contact, electrons and holes diffuse into PPy and MoS2, respectively, contributing to generating output voltages and currents. To increase the number of charges diffusing across the p–n junction, Ag nanoparticles (NPs) and a piezoelectric poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) layer were placed below MoS2. Additionally, PPy was p-doped using Pt NPs. These MoS2-based TENGs exhibited an instantaneous power density of 14.4 mW cm−2 with an external load resistor of 1 MΩ and a transferred charge density of 0.047 μC cm−2 in a single cycle when charging a capacitor. These values are higher than the previously reported values, demonstrating that tribodiffusion-based TENGs can be regarded as another type of TENG.

Bio-triboelectric nanogenerators (bio-TENGs) have become one of the choices of energy supply for new electronic devices, but the relationship between the internal crystalline structure of bio-derived materials and the triboelectric performance has not been investigated. In this paper, microbial polyhydroxybutyrate (PHB) with special wrinkled spherulites is prepared by a high-pressure solid-state forming method, which unexpectedly facilitates the contact electrification of PHB. When the PHB-based TENG is stimulated, the intrinsic micro-/nanoscale dual crystalline structure of wrinkled spherulites enables significant improvement of the surface charge density of PHB. The open-circuit voltage and short-circuit current of the high-pressure crystallized PHB based TENG are around 5 and 12 times higher than those of the normal-pressure crystallized PHB-based TENG, respectively. Moreover, the bio-TENG shows remarkable stability and durability, and can be utilized as a reliable power source to drive commercial LEDs. In particular, the self-powered TENG sensor based on high-pressure crystallized PHB exhibits great prospects for monitoring and recognizing human athletic motions. This work shows that there is a simple but novel method to improve the performance of bio-TENGs, which not only determines the relationship between the crystalline structure of biomaterials and triboelectricity, but also provides a new insight for developing high-performance and environment-friendly electronic devices.

Triboelectric nanogenerators (TENGs) have opened a new direction in the field of flexible devices. Here, a fluorescent TENG–JNA constructed with a flexible Janus nanobelt array (JNA) and PVDF/PVP nanofibers membrane by electro-spinning is reported for the first time. The building unit of JNA is the [PANI/CNTs/PMMA]//[Tb(BA)3phen/PMMA] Janus nanobelts, which demonstrate green fluorescence and electrical conduction bi-function, where two independent partitions are microscopically realized in the Janus nanobelts. In TENG–JNA, JNA concurrently gains excellent charge-trapping ability and charge-generating capability by optimizing the PANI content; therefore, JNA serves as both a charge-generating layer and charge-trapping layer. The interface between TB(BA)3phen and PMMA, the existence of aromatic ring structures in the PANI main chain and the interface between PANI and PMMA are conducive to trap a large number of triboelectric charges in time to prevent the triboelectric charges from combining with induced charges, which can significantly improve the output performance of TENG–JNA. The maximum output current and voltage of TENG–JNA are 6.20 μA and 155 V, respectively. The introduction of Tb(BA)3phen ensures the strong fluorescence of TENF–JNA, and this fluorescence can be used to judge whether TENF–JNA works normally or is out of order in a dark environment. TENG–JNA possesses other compelling features, such as prominent flexibility, good hydrophobicity, durability and light weight, which provides the premise for TENG–JNA to be used as a flexible device in a wet environment or for warning functions. The Janus nanobelt was firstly used to assemble a TENG, which provides theoretical, material and technical support for the development of new building units of TENGs and paves a pathway for designing and assembling new TENGs.

Biomonitoring has played an increasingly important role in improving the quality of healthcare in recent years, but limitations in power supply and wearability, as well as the rise of the Internet of Things (IoT) have called for the development of a new type of device to provide biomonitoring on a daily basis. While the introduction of triboelectric nanogenerators (TENGs) has begun to solve these issues by providing sustainably powered biomonitoring, textile-based TENGs (tTENGs) take a more pervasive approach by integrating this technology into commonly worn textiles. tTENGs are particularly unique as they offer an inexpensive alternative for biomonitoring; the high breathability, comfort, and scalability inherent to tTENGs' woven structures have made them increasingly convenient for human application. This review begins by highlighting novel material configurations of tTENGs and their advantages for biomonitoring. We then discuss various wearable tTENG devices that have been adapted for constant cardiovascular and respiratory monitoring, pertinent to those suffering from diseases in these organ systems. Transitioning into the biomechanical aspect of the human body, we explore tTENG configurations integrated for upper body and gait motion sensing. At the same time, with many people suffering from sleep disorders, we examine tTENGs that monitor the quality of sleep of an individual. Lastly, on a more molecular level, we examine the application of tTENGs for monitoring biochemical fluctuations, such as sweat. Finally, we discuss the future research directions for the field, in particular regarding personalized healthcare propelled by tTENGs.

The timely biochemical detection of environmental pollutants or infectious disease is a predominant challenge for global health and people living in remote areas. However, the energy supply is still difficult for both the pretreatment and test steps, especially for diagnostics in resource-limited environments or outdoor point-of-care testing. Herein, we demonstrate a hand-powered triboelectric nanogenerator (TENG) system, which can simultaneously accomplish centrifugal pretreatment and analysis without an additional power supply. The complete separation of plasma from red blood cells can be achieved within 1.5 min at an operation frequency of 1 Hz. Besides, according to the impressive high rotational speed of 7500 rpm, the rotating mechanical energy can be efficiently recycled by the TENG to power different electronic devices, such as an electronic watch or thermometer. As a demonstration, the pretreatment of lake water and the detection of hydrogen peroxide contained in it has been realized. The combination of the system with different types of sensors will further promote its applications in multifarious biochemical detections. Moreover, this TENG system is effective, field-portable and ultra-low cost, and is promising for battery-free point-of-care diagnostic systems for outdoor or harsh environments.

Precisely controlling the coordination microenvironment and electronic features of polynuclear secondary building units (SBUs) in coordination polymers (CPs) is an efficient approach to governing their fundamental performance. Here, different multinuclear SBUs (binuclear, trinuclear, and pentanuclear SBUs for 1-3, respectively) were introduced into Cd-based CPs, which were used as frictional electrode materials, to clarify the contributions of polynuclear Cd-SBUs through the output of triboelectric nanogenerators (TENGs). The results demonstrated that 1-TENG with binuclear Cd-SBUs possessed the highest output, whereas 3-TENG with the pentanuclear Cd-SBUs indicated the minimum output, suggesting that the binuclear Cd-SBUs in 1 lost electrons most readily and generated much more charge, which was further confirmed by density functional theory calculations. This work opened a new prospect to confirm the gaining/losing capability of polynuclear Cd-SBUs in CPs and provided an effective approach to tuning both the stability and functionality of polynuclear CPs as frictional pair materials to regulate the output of CPs-based TENGs.