Self-powered Sensor Research Articles

In-situ cured gel polymer/ecoflex hierarchical structure-based stretchable and robust TENG for intelligent touch perception and biometric recognition

Gel-based sensors for next generation touch panels have been acknowledged for their exceptional sensitivity and flexibility. However, these sensors typically depend on a metal grid connection, which is susceptible to structural deformation under heavy stress applications and necessitates external power. Here, we report a novel in-situ cured gel polymer electrode-based triboelectric nanogenerator (GPE-TENG) that is stretchable, semi-transparent, and durable, designed to enable a self-powered touch panel for intelligent touch perception. The in-situ curing of the hierarchical structure of the ionic polymer gel encapsulated within the ecoflex ensures robust adhesion of the ionic conductive polymer gel (PEO/LiTFSI) to the ecoflex layers, addressing the issue of delamination in TENG components under mechanical stress. As a result, the GPE-TENG demonstrates high durability, enduring under stretching of approximately 375 % and sustaining heavy mechanical deformations (under folding, twisting, and rolling) over a long period (approximately 2 months) without loss of functionality. Remarkably, the GPE-TENG exhibits outstanding energy harvesting capabilities with a peak power density of 0.36 W m-2. Notably, the GPE-TENG generates electrical signals through simple device stretching, thus serving as a self-powered wearable sensor for human activity monitoring. Moreover, a 9-digital arrayed (3 × 3) flexible, semi-transparent, and self-powered touch panel based on the GPE-TENG shows multifunctionality, including touch track/pattern recognition (i.e. touch and sliding mode) and a highly accurate (∼98 %) deep learning assisted smart biometric system for user identification.

Self-healable and stretchable perovskite-elastomer gas-solid triboelectric nanogenerator for gesture recognition and gripper sensing

Gas-solid triboelectric nanogenerators (GS-TENGs) based on porous elastomers provide a promising avenue for the design of self-powered sensors. However, the intrinsic limitation of low electric output in GS-TENGs could affect the accuracy and sensitivity of sensing systems. Here, we develop a porous composite by integrating an adhesive poly(siloxane-diphenylglyoxime-urethane) (PSDU) elastomer with ferroelectric (3,3-difluorocyclobutylammonium) 2 CuCl 4 [(DF-CBA) 2 CuCl 4 ] fillers. PSDU, an intrinsically triboelectric negative material with alternating hard-soft segments and supramolecular bonds, imparts excellent compressibility, adhesion, and self-healing properties to the composite. Simultaneously, the incorporation of (DF-CBA) 2 CuCl 4 as functional fillers leverages the formation of a hydrogen bonding network to enhance charge transfer processes. These fillers facilitate charge accumulation through an electric poling process, resulting in a power output improvement that surpasses 1400 times higher than that of a dense PSDU-based GS-TENG. Tapping onto the versatile properties of porous poly(siloxane-diphenylglyoxime-urethane)-perovskite (PSDU-PK) GS-TENGs, applications such as hand gesture/food recognition and dual-mode sensing system have been demonstrated, suggesting their promising potential in wearable electronics and smart agriculture.

Intact photosynthetic bacteria-based electrodes for self-powered metal ions monitoring

The low-cost and early monitoring of metal ion contaminants is paramount to prevent widespread contamination of water environments. Self-powered microbial electrochemical sensors represent an interesting approach to achieving this goal. Purple non-sulfur bacteria have a versatile metabolism and a well-characterized photosynthetic system, making them an ideal candidate for developing biohybrid technologies. In this work, we report the use of these bacteria in biophotoelectrodes to develop self-powered monitoring systems for two common pollutants, NiCl2 and CuSO4. The microbial biophotoelectrode was obtained on a homemade poly-hydroxybutyrate-carbon nanofibers electrode modified with a redox-adhesive polydopamine matrix-based entrapping the purple bacterium Rhodobacter capsulatus. The presence of 500 μM NiCl2 resulted in a 60 % decrease in current density, while the simultaneous presence of 100 μM NiCl2 and 100 mM CuSO4 led to an 83 % current inhibition. Given the implementation of the biophotoelectrode in the field, the biohybrid system was tested in a complex matrix containing beer, demonstrating the promising ability of the photoelectrochemical system to act as an efficient biosensor in complex solutions. Finally, the biohybrid electrode was coupled to a cathode performing oxygen reduction, which allowed obtaining a self-powered monitoring system, paving the way for the future implementation of a low-cost monitoring system for widespread metal ions contaminant monitoring.

An In2O3/In2S3 photoanode-driven whole-cell biocathode sensor for sensitive detection of nitrate

Whole-cell biocathode sensor is a new form of self-regenerable biosensor and promising for environmental monitoring especially in the scenario with low organic substrate. However, external power supply such as electrochemical workstation is required to drive the biocathode reaction, which greatly limits its application. Herein, a new strategy based on the visible-light-driven whole-cell biocathode was proposed and validated for self-powered sensitive detections. To be specific, 1-OH phenazine was selected as the optimal electron shuttle for a Shewanella oneidensis MR-1 inoculated biocathode, which efficiently mediate the cathodic reaction at an electrode potential below −0.6 V (vs. SCE). Meanwhile, an In2O3/In2S3 photoanode with nanoflower-like structure was fabricated to match the kinetic of the biocathode. The photo-driven biocathode reduction was convinced by comparing with the performance of biocathode in the conventional three-electrode system. With this basis, a self-powered whole-cell biocathode sensor was developed for nitrate detection. An extreme low limit of detection of 0.028 μM (S/N=3) and linear detection range of 0.1–20 μM was achieved. Moreover, this biocathode sensor also exhibited excellent selectivity, reusability, accuracy, stability and was reliable for the detection of complex environmental samples. Therefore, this work developed a new photo-driven whole-cell biocathode sensor with excellent detection capacity of nitrate, which opens up new prospects for the development of high-performance biosensors.

Sensitive detection of persulfate by a novel self-powered electrochemical sensor with carbon cloth electrodes modified with tin-doped cobalt tetroxide.

The accurate and rapid detection of persulfate concentration is important for environmental decontamination and human health protection. In this work, a novel self-powered electrochemical sensor for the sensitive monitoring of persulfate was developed, which utilized cobalt tetroxide (Co3O4@CC) or tin-doped cobalt tetroxide (SnxCo3-xO4@CC) cathode as the sensing element and anode with electrogenic microorganisms as the power supplier. The Co3O4@CC and SnxCo3-xO4@CC electrodes were fabricated by in situ growing nanostructured Co3O4 or SnxCo3-xO4 catalysts on carbon cloth. Electrochemical tests revealed that these electrodes exhibited excellent catalytic reduction performance toward persulfate because of the synergistic catalysis by Co3O4 and electrode electrons, well-exposed Co2+/Co3+ catalytic sites, and high electron transfer efficiency. Tin doping could enhance the catalytic persulfate reduction by improving the conductivity and electron transfer of the Co3O4 catalyst. The electrode prepared at a hydrothermal temperature of 90°C and a tin dosage of 0.286g·cm-2 achieved the highest persulfate reduction activity under pH 7. The sensing properties of the self-powered sensors toward persulfate were explored in detail. Results showed that under the optimal external load of 300 Ω, the proposed sensor could display a broad detection range of 0 to 1500μmol L-1 K2S2O8 with sensitivities of 1.13 and 0.12 μA μmol-1 L, a detection limit of 1.11μmol L-1 (S/N = 3), and a fast response time within 30s. The sensors also presented satisfactory reproducibility and selectivity during the detection of persulfate. The proposed sensor will provide a new approach for sensitive, on-site, and real-time monitoring of persulfate for a wide range of applications.

Self-powered, highly selective and fast response time ammonia gas sensors based on an rGO/SnO2 nanocomposite

Improving the sensitivity and selectivity of ammonia gas sensors at room temperature is essential for the development of self-powered sensors to expand their operational range in various environments. The strategy employed in this study to achieve this goal involves combining reduced graphene oxide (rGO), known for its excellent electrical properties, with SnO2, which has been reported to have ammonia-sensing capabilities. For this purpose, the rGO-SnO2 nanocomposite was synthesized using a two-step pyrolysis and chemical deposition method, and its ammonia gas sensing performance was evaluated. Structural characterization of the synthesized sample was conducted using XRD, BET, SEM, PL, EDX and FTIR techniques. The sensor's response to different concentrations of ammonia gas at room temperature was investigated, and the results showed a 5.2% response at 800 ppm and a low detection limit of 1.43 ppm for this gas. In addition to its high selectivity for ammonia gas, the sensor also demonstrated stability and repeatability.

Triboelectric Nanogenerator for Self-Powered Gas Sensing.

With the continuous acceleration of industrialization, gas sensors are evolving to become portable, wearable and environmentally friendly. However, traditional gas sensors rely on external power supply, which severely limits their applications in various industries. As an innovative and environmentally adaptable power generation technology, triboelectric nanogenerators (TENGs) can be integrated with gas sensors to leverage the benefits of both technologies for efficient and environmentally friendly self-powered gas sensing. This paper delves into the basic principles and current research frontiers of the TENG-based self-powered gas sensor, focusing particularly on innovative applications in environmental safety monitoring, healthcare, as well as emerging fields such as food safety assurance and smart agriculture. It emphasizes the significant advantages of TENG-based self-powered gas sensor systems in promoting environmental sustainability, achieving efficient sensing at room temperature, and driving technological innovations in wearable devices. It also objectively analyzes the technical challenges, including issues related to performance enhancement, theoretical refinement, and application expansion, and provides targeted strategies and future research directions aimed at paving the way for continuous progress and widespread applications in the field of self-powered gas sensors.

A piezoelectric oscillator for low-speed wind energy collection

ABSTRACT The exploration of low-speed wind harvesters is key to harnessing wind energy and enabling self-powered Internet of Things (IoT) sensor networks. In this paper, a piezoelectric oscillator (APO) for low-speed wind energy collection (B-WEC) is proposed and applied to low-speed wind energy harvesting. The magnetic model and power generation characteristics of the harvester are formulated, the magnetic torque is simulated, and the performance under different parameter combinations is tested experimentally. The results show that the APO rotation reduces the magnetic resistive torque by 26.00%. The highest peak-to-peak voltage is 92.35 V for an APO magnet diameter is 8 mm and the angle of the stopper (γ) is 60°, which is 1258.09% higher than fixed (γ is non-existent). Moreover, it has a maximum power of 0.56 mW at 4 m/s, and the optimally matched resistance is 200 kΩ. The harvester can light up about 150 LEDs. The B-WEC designed in this paper can effectively reduce the driving wind speed of piezoelectric wind energy harvesters and can be used as a power source for self-powered networked sensor networks. This study provides a new solution idea for the exploitation of wind energy.

A Photovoltaic Self-Powered Volatile Organic Compounds Sensor Based on Asymmetric Geometry 2D MoS2 Diodes

Transition metal dichalcogenides have gained considerable interest for vapour sensing applications due to their large surface-to-volume ratio and high sensitivity. Herein, we demonstrate a new self-powered volatile organic compounds (VOC) sensor based on asymmetric geometry multi-layer molybdenum disulfide (MoS2) diode. The asymmetric contact geometry of the MoS2 diode induces an internal built-in electric field resulting in self-powering via a photovoltaic response. While illuminated by UV-light, the sensor exhibited a high responsivity of ∼60% with a relatively fast response time of ∼10 sec to 200 ppm of acetone, without an external bias voltage. The MoS2 VOC diode sensor is a promising candidate for self-powered, fast, portable, and highly sensitive VOC sensor applications.

Portable self-powered electrochemical aptasensor for ultrasensitive and real-time detection of microcystin-RR based on hydrovoltaic-photothermal coupling effect

Coupling different energy harvesting technologies to obtain an excellent output signal is essential for the development of high-performance self-powered electrochemical sensors. Herein, a novel hydrovoltaic-photothermal coupling self-powered electrochemical aptasensing platform was designed for sensitive detection of microcystin (MC-RR) with a digital multimeter as a direct visual readout strategy. The straightforward ultrasonic method was employed to synthesize polyaniline (PANI) and bismuth oxybromide (BiOBr) nanosheets, which were then integrated as active components in a hydrovoltaic device. The unique layer structure of two-dimensional (2D) nanomaterials BiOBr can create flexible interlayer spaces to accommodate various ions and water molecules, which was beneficial to construct evaporation-driven channels. Meanwhile, the exceptional photothermal characteristics of polyaniline could accelerate the water evaporation rate, consequently boosting the migration speed of charge carriers and increasing output signal. Moreover, a digital multimeter was connected to the constructed sensor for real-time displaying the output signal. With the assistance of aptamer, a novel self-powered electrochemical aptasensing platform was constructed for sensitive detection of MC-RR. Under optimum conditions, the output signal of the hydrovoltaic-photothermal coupling cell was linearly related to the logarithm of MC-RR concentration in the range of 1 fM to 1 nM with a detection limit of 0.31 fM (S/N = 3). Furthermore, this sensor also exhibited many advantages such as high selectivity, good repeatability and portability. Such novel strategy not only offers a completely new general approach to construct high-performance self-powered devices for the detection of MC-RR, but also provides a new strategy for advancing the miniaturization and field application of self-powered electrochemical sensors.

Reversibly Compressible Silanated Cellulose Nanofibril Aerogel for Triboelectric Taekwondo Scoring Sensors.

The integration of bio-based materials into triboelectric nanogenerators (TENGs) for energy harvesting from human body motions has sparked considerable research attention. Here, a silanated cellulose nanofibril (SCNF) aerogel is reported for structurally reliable TENGs and reversely compressible Taekwondo scoring sensors under repeated impacts. The preparation of the aerogel involves silanizing cellulose nanofibers (CNFs) with vinyltrimethoxysilane (VTMS), following by freeze-drying and post-heating treatment. The SCNF aerogel with crosslinked physico-chemical bonding and highly porous network is found to exhibit superior mechanical strength and reversible compressibility as well as enhanced water repellency and electron-donating ability. The TENG having a tribo-positive SCNF layer exhibits exceptional triboelectric performances, generating a voltage of 270V, current of 11µA, and power density of 401.1mWm-2 under an applied force of 8N at a frequency of 5Hz. With its inherent merits in material composition, structural configuration, and device sensitivity, the SCNF TENG demonstrates the capability to seamlessly integrate into a Taekwondo protection gear, serving as an efficient self-powered sensor for monitoring hitting scores. This study highlights the significant potential of a facilely fabricated SCNF aerogel for the development of high-performance, bio-friendly, and cost-effective Bio-TENGs, enabling their application as self-powered wearable devices and sports engineering sensors.

Thermogalvanic hydrogel with controllable ion confined transportation and its application for self-powered lactic acid sensor

Low-grade heat energy (below 100 °C) is abundantly available in the natural environment, yet effective utilization remains challenging. Liquid-state thermocells, also known as thermo-electrochemical cells or thermogalvanic cells, have emerged as promising solution for converting low-grade heat into electrical energy due to their high Seebeck coefficients (mV·K–1). However, traditional liquid-state thermocells suffer from the issue of liquid leakage caused by frequent cooling or heating during operation. Here in this work, we propose thermogalvanic hydrogels through introducing redox ions into hydrogel framework. The thermoelectric performance of the proposed hydrogel is highly dependent on the ion concentration, which is attributed to the confined ion transportation in micro/nano channels caused by the salting out effect. After the optimization of thermoelectric parameters, a Π-shaped thermocell composed of three p-n pairs is fabricated to harvest low-grade body heat energy. An open-circuit voltage of 163 mV, a short-current density of 0.7 mA·m–2 and a maximum power density of 26.7 μW·m–2 are achieved at a temperature difference of 30 K. To further demonstrate the practical potential, the thermoelectric generator is integrated with a lactic acid sensor to sensitively detect the lactic acid concentration without any external power supplies.

Self-powered microfluidic-based sensor for noninvasive sweat analysis

This study introduces a novel self-powered, microfluidic sweat sensing system. The device features a flexible thermoelectric system that enables efficient on-demand sweat extraction and data transmission. Both the thermoelectric generator (TEG) and the microfluidic system are thoroughly evaluated through numerical simulations and experimental testing. The device integrates electrochemical sensors for glucose, pH, and ion detection, along with solid-liquid triboelectric nanosensors to measure sweat rate. It demonstrates high selectivity for target analytes. Sweat, extracted via iontophoresis with carbagel, interacts with electrodes coated with ion-selective membranes (ISM) and glucose oxidase, producing an open-circuit potential. This selective detection of analytes results in distinct output differences. Additionally, the device delivers stable results within 20 minutes, reducing analysis time while maintaining a strong correlation with blood biomarker concentrations. This partially flexible, noninvasive system has potential applications in monitoring electrolyte loss and glucose imbalances through sweat.

A wearable, self-sustainable, and wireless plantar pressure and temperature monitoring system for foot ulceration prognosis and rehabilitation

Continuous foot temperature and pressure monitoring are desirable for prevention and care of foot health conditions such as Diabetic foot ulceration (DFU). However, monitoring these parameters simultaneously is complex, and mostly rely on sensors with undisrupted power supply integration. Herein, we propose high-performance self-sustainable smart footwear capable of monitoring foot pressure and temperature at various locations for real-time applications. The footwear consists of three modules of an integrated electromagnetic generator (EMG) and triboelectric (TENG) self-powered pressure sensors operated by very elastic 3D printed thermoplastic polyurethane (TPU) springs formed by stacking circular plates that allow TENG pressure sensors to be embedded within. Additionally, Laser-induced graphene (LIG) temperature sensors are used for monitoring foot temperature. The embedded EMG can deliver high output power during various activities: walking (38 mW), running (154 mW), and jumping (75 mW), sufficient to power signal processing and transmission circuitries for wireless monitoring of foot temperature and pressure. TENG-based pressure sensors and LIG temperature sensors (LTS) embedded in this design allow mapping of foot pressure (0.2 V/kPa at 1 Hz) and foot temperature (0.55 Ω °C−1) continuously. Finally, footwear was assembled successfully to demonstrate wireless self-sustainable multisensory smart footwear for monitoring foot pressure and temperature to prevent and rehabilitate diabetic foot ulcers.

Self-Powered Flexible Edible UV Sensors Based on Sustainable Materials Applicable for Food Packaging

Self-Powered Flexible Edible UV Sensors Based on Sustainable Materials Applicable for Food Packaging

Self-powered flexible sensor network for continuous monitoring of crop micro-environment and growth states

Monitoring crops’ micro-environment and growth states is significant for developing smart agriculture. However, the traditional rigid and large-sized sensor systems cannot meet the demands of precision agriculture for multi-parameter and high-throughput monitoring. Here, we integrate a flexible sensor system with low-power communication techniques, designing a two-layer star topology sensor network based on BLE and NB-IoT protocol. The sensors are arranged on flexible substrates, allowing them to closely adhere to various parts of crops, such as stems and leaves. To ensure the accuracy of the sensors, they are evaluated and calibrated in the laboratory. A solar energy harvesting system is designed for the sensor network to make it self-powered and successfully measure temperature, humidity, illumination, and leaf angles stably, demonstrating the system’s feasibility. The deployment cost of the sensor network is significantly lower than that of traditional automatic weather stations, showcasing its potential for widespread application in farmlands.

Multifunctional organohydrogels enabling sensitive strain sensing and self-powered triboelectricity

Hydrogels have broad application prospects in portable strain sensors and triboelectric nanogenerators (TENG), and have attracted great attention in the field of wearable electronic devices and energy transfer devices. However, the development of multifunctional gels that can meet a variety of application scenarios is still a challenging problem. In this study, a multifunctional poly(acrylamide-co-2-acrylamide-2-methylpropanesulfonic acid)/lignosulfonate/Zr4+ organohydrogel noted as “P(AM-co-AMPS)/LS/Zr4+” was fabricated based on dynamic metal coordination bonds and hydrogen bonds, which could be used as flexible strain sensor and TENG electrode material. The organohydrogel based strain sensor could monitor both large and tiny human movements due to the high sensitivity (GF = 4.37, up to 200 %) and circulation stability. The assembled organohydrogel-based triboelectric nanogenerator (O-TENG) could generate an open-circuit voltage of 70.47 V and a short-circuit current of 25.21 μA. It is worth mentioning that the O-TENG could light up 44 LED bulbs by tapping with the palm at −20 °C, and the electronic output performance of the O-TENG after self-healing was unaffected. Additionally, the O-TENG exhibited enormous potentials in the biomechanical energy harvesting and self-powered motion sensors in the areas of human movements detection, human–computer interaction, electronic skin and self-powered devices.

Polymer-metal film induced ultrahigh output TVNG and self-powered intelligent sensor system assisted by EEMD

Tribovoltaic nanogenerators (TVNGs) based on tribovoltaic effect can output DC current directly, and has the advantages of high output current density and low internal resistance. While TVNGs have been restricted by its low output voltage and power. Herein, we have developed a metal-polymer film with a micro-uneven structure on the surface, much higher corrosion resistance and wear resistance than metal. On this basis, a centimeter-level sliding structure metal-EP/GaN-TVNG has been fabricated, which shows a high and stable long-term DC electrical output (a maximized power output of 4.19 W/m2 when matched with a 0.07 MΩ resistor, a stable output current of 2.25 A/m2 and a peak Voc of 27 V). Further, a TVNG vehicle travelling intelligent sensor and system which can integrate electrical signals collected by TVNG into digital signal processing algorithms and then feed backing to the driving system, has been designed and manufactured. As an effective method for deep analysis of signals, Ensemble Empirical Mode Decomposition (EEMD) has been used for the first time for deep processing of nanogenerator signals in this work. This work provides a new model of further development of high output TVNG and a new deep signal processing methods of TVNG/TENG signal.

Efficient Permeable Monolithic Hybrid Tribo-Piezo-Electromagnetic Nanogenerator Based on Topological-Insulator-Composite.

Escalating energy demands of self-independent on-skin/wearable electronics impose challenges on corresponding power sources to offer greater power density, permeability, and stretchability. Here, a high-efficient breathable and stretchable monolithic hybrid triboelectric-piezoelectric-electromagnetic nanogenerator-based electronic skin (TPEG-skin) is reported via sandwiching a liquid metal mesh with two-layer topological insulator-piezoelectric polymer composite nanofibers. TPEG-skin concurrently extracts biomechanical energy (from body motions) and electromagnetic radiations (from adjacent appliances), operating as epidermal power sources and whole-body self-powered sensors. Topological insulators with conductive surface states supply notably enhanced triboelectric and piezoelectric effects, endowing TPEG-skin with a 288V output voltage (10 N, 4Hz), ∼3 times that of state-of-the-art devices. Liquid metal meshes serve as breathable electrodes and extract ambient electromagnetic pollution (±60V, ±1.6µA cm-2). TPEG-skin implements self-powered physiological and body motion monitoring and system-level human-machine interactions. This study provides compatible energy strategies for on-skin/wearable electronics with high power density, monolithic device integration, and multifunctionality.

Broadband elastic energy harvesting based on achromatic meta-grating

Energy harvesting exploiting the inverse piezoelectric effect has been the subject of much attention and discussion in the field of elastic and structural dynamics. Recently, the ongoing development of elastic metamaterials and metasurfaces has opened up a new way to improve the quality of energy harvesting. Here, we proposed a new strategy for harvesting elastic energy in a plate, which is the use of the inverse piezoelectric effect to convert the elastic energy into electrical energy after the achromatic meta-grating has focused broadband flexural waves. A new theoretical method to design the achromatic meta-grating is proposed based on derived analytical expression of the phase shift of subunit. When a meta-grating, a thin plate and a piezoelectric patch are combined into an energy harvesting system, the elastic energy can be converted into electric energy by the system, and the output voltage can be amplified by twice that of the system without the meta-grating. A theoretical framework is built to analyze the performance of the energy harvesting system, and variational parametric analyses are carried out to obtain the optimal resistance, the optimal length, thickness and position of piezoelectric patch, which are 870Ω, 18mm, 0.2mm and 30mm, respectively. For the optimized system, the power harvested rate of the system is close to 4 in the frequency band of 6-8kHz. Finally, the design of the system based on the wave focusing principle is extended, and energy harvesters are designed for different frequency bands, which can all work under different excitation conditions (a local and a base excitations). Our work opens up a new route for elastic energy harvesting and may have broad application prospects in the development of self-powered sensors.