Thermoelectric Microgenerators Research Articles

A Hybrid Harvesting Method for Multiple Marine Renewable Energy Sources Based on Microthermoelectric Generator and Triboelectric Nanogenerator

Harvesting wind and solar energy in marine environments to power marine sensors has become a hot research topic. Herein, a marine hybrid energy gathering method based on codoped microthermoelectric generator (MTEG) and charge‐enhanced triboelectric nanogenerator (TENG) is proposed. A prototype based on this method is designed. It consists of an MTEG unit made from codoped Bi2Te3‐based thermoelectric materials and a TENG unit equipped with a charge density enhancement circuit. This prototype can simultaneously harvest solar energy and wind energy in marine environments to power marine sensors. The prototype can generate a voltage output of 72 V and a power output of 90.5 μW under experimental conditions featuring a wind velocity of 5 m s−1 and a temperature difference of 50 K. This results in a harvesting energy density of 9 W m−3. Based on experiments, the feasibility of the hybrid energy gathering method presented herein is verified, offering a new approach for powering marine sensors.

Advanced Energy Modeling and Prediction of Integrated Micro-Generator System for Useful Heat Harvesting

Theoretical modeling and numerical simulation of an integrated micro-thermoelectric generator system for thermal power generation are carried out. The system measures 4.2 × 4.2 × 5 mm and consists of a micro-thermoelectric module (bismuth telluride) and two finned heat sinks (aluminum). The system can be used to convert thermal energy to electricity in Seebeck effect-based micro-applications. This work aims to improve an advanced model to effectively predict the thermal performance of the system and to develop thermal and flow simulations to accurately evaluate real micro-thermoelectric generator systems. The advanced model solves the thermoelectric module’s energy equations, incorporating heat balance in the heat transfer calculations. The thermal and flow simulations take into account the dynamic calculations under the thermal loads occurring in the system. This innovative aspect can considered separately for the different materials (ceramics, semiconductors and copper strips) of the micro-thermoelectric module for heat transfer enhancement. The results predicted that when the temperature difference of the thermoelectric module was increased from 18 K to 58 K, the power output and the conversion efficiency of the system increased by about 0.5 W and 50%, respectively. Also, the transfer of useful heat to electrical power was achieved at 83%, with 11% saved heat and thermal losses of 6% W at maximum temperature difference of the module. In terms of overall energy consumption, the integrated micro-thermoelectric generator system has a little environmental impacts. Validation of the model with particular experimental works was accomplished for dependability. Comparisons with different modeling strategies demonstrate that the accuracy and performance of the advanced model can be used to reliably study the thermal performance of real micro-thermoelectric generator systems.

An underwater wake sensing method based on Micro Thermoelectric Generator for enhancing recognition accuracy

The accidental entry and poaching of foreign boats and autonomous underwater vehicles (AUVs) have a detrimental impact on the ecological environment of marine ranching. Currently, there is a need for a monitoring method specifically designed to monitor underwater moving objects (UMOs), such as foreign boats and AUVs, in real-time within marine ranching. Therefore, this paper creatively proposes a method for monitoring UMOs based on thermal tactile of Micro Thermoelectric Generator (MTEG). A thermal tactile perceptual model for propeller wake identification is established and the wake sensing sensor (WSS) is designed. Furthermore, the performance verification experiment of wake sensing and the target classification experiment based on machine learning are carried out to prove the feasibility of the method. The experimental results demonstrate that the propeller wakes are identified with an accuracy of more than 90 % within 30 s in the monitoring terminal. Besides, the method can accurately distinguish between propeller wakes and fish wakes, thereby avoiding false alarms. The reported underwater wake sensing method is a new solution to real-time monitoring and safety early warning of marine ranching.

Manufacturing and measurement of CMOS-MEMS-based micro thermoelectric generators with long-length thermocouples

The study explores the fabrication and evaluation of a micro thermoelectric generator (MTG) with long-length thermocouples (TCs) through the utilization of a commercial complementary metal oxide semiconductor process. The MTG consists of 23 TCs, and its performance is intricately linked to the temperature difference (T diff) between the cold and hot sides of these TCs. An increase in T diff leads to higher output voltage and power for the MTG. To enhance T diff, the TCs are designed to be 700 µm in length, and an innovative design has been implemented on the cold side of the TCs, creating a suspended structure to improve heat dissipation A post-process is essential for achieving this suspended TC structure. The results demonstrate that the TC structure is fully suspended and remains undamaged. The measured outcomes reveal an output voltage of 13.8 mV when the T diff reaches 3.5 K. Under these conditions, the MTG exhibits a voltage factor of 2.76 mV mm−2K−1. Furthermore, at a T diff of 3.5 K, the maximum output power reaches 2.1 nW. The MTG demonstrates a power factor of 0.12 nW mm−2 K−2.

A hybrid energy harvesting approach for transmission lines based on triboelectric nanogenerator and micro thermoelectric generator

To effectively detect faults in transmission lines, monitoring the operating status of these lines is imperative. However, providing power to monitoring devices for transmission line status presents a significant challenge. In this research, a hybrid energy harvesting approach based on micro thermoelectric generator (MTEG) and triboelectric nanogenerator (TENG) is proposed, and a theoretical model for MTEG-TENG hybrid energy harvesting is established. This study develops an integrated energy harvesting prototype, which incorporates oscillating-TENG (O-TENGs), MTEGs, and a power management control unit. This prototype not only harvests energy from the vibrations of transmission lines but also converts the lines thermal energy into electricity. The Experiment results show that the maximum open-circuit voltages of O-TENG and MTEG reach 80.3 V and 1.094 V, respectively. Compared to a single MTEG energy harvesting device, the prototype of the MTEG-TENG hybrid energy harvesting device demonstrates a 5.36% improvement in energy harvesting and battery charging performance. Consequently, this approach achieves self-powered monitoring with excellent stability and lower manufacturing costs. It provides an efficient and durable power approach for transmission line status monitoring devices.

Self‐Powered Vibration Frequency Monitoring Device for the Grid Based on Triboelectric Nanogenerator and Micro Thermoelectric Generator

AbstractThe galloping of transmission lines (GTLs) has a significant impact on the development of smart grids. However, traditional vibration frequency monitoring devices for transmission lines suffer from issues such as low measurement accuracy, high environmental requirements, and the inability to achieve self‐powering. A self‐powered vibration frequency monitoring method is proposed based on frequency‐sensing triboelectric nanogenerator (F‐TENG) and micro thermoelectric generators (MTEG). Models for vibration frequency sensing based on F‐TENG and energy capture based on MTEG are established. A flexible self‐powered sensing prototype, integrating F‐TENG, MTEG, and a Signal processing and Energy harvesting Circuit (SEC), is fabricated. Additionally, an innovative solvothermal method for the preparation of MTEG materials is presented, resulting in Bi2Te3‐based thermoelectric materials with significantly high thermoelectric conversion performance. Experimental results demonstrate that within the range of 0.1–5.1 Hz, F‐TENG can precisely perceive the frequency of GTLs, with a maximum error of 1.274%. MTEG achieves a maximal open‐circuit voltage of 3.282 V. Finally, the SEC unit is designed to couple the outputs of F‐TENG and MTEG for frequency calculation and wireless transmission to a microcontroller. This device provides an efficient solution for monitoring the frequency of GTLs and offers robust support for the stability of the smart grid.

Planar Thermoelectric Microgenerators in Application to Power RFID Tags.

This paper presents an innovative approach to the integration of thermoelectric microgenerators (μTEGs) based on thick-film thermopiles of planar constantan-silver (CuNi-Ag) and calcium cobaltite oxide-silver (Ca3Co4O9-Ag) thick-film thermopiles with radio frequency identification (RFID) technology. The goal was to consider using the TEG for an active or semi-passive RFID tag. The proposed implementation would allow the communication distance to be increased or even operated without changing batteries. This article discusses the principles of planar thermoelectric microgenerators (μTEGs), focusing on their ability to convert the temperature difference into electrical energy. The concept of integration with active or semi-passive tags is presented, as well as the results of energy efficiency tests, considering various environmental conditions. On the basis of the measurements, the parameters of thermopiles consisting of more thermocouples were simulated to provide the required voltage and power for cooperation with RFID tags. The conclusions of the research indicate promising prospects for the integration of planar thermoelectric microgenerators with RFID technology, opening the way to more sustainable and efficient monitoring and identification systems. Our work provides the theoretical basis and practical experimental data for the further development and implementation of this innovative technology.

Overall numerical simulation of chemical-thermal-electric conversion for an all-in-one thermoelectric generator based on micro scale combustion

Micro combustion-based power systems have garnered significant attention owing to their high energy density and portability. This work presents a numerical simulation process for an integrated thermoelectric generator based on micro-combustion, which can track the chemical-thermal-electro energy conversion. The combustion performance, thermal characteristics and energy conversion for the micro-thermoelectric generator (MTEG) system are investigated. A range of equivalence ratios and Reynolds numbers (Re) is examined to provide a detailed analysis. With the increment of equivalence ratio (φ), both the energy output and the open-circuit voltage of the system significantly increase. At high φ, the voltage and energy output exhibit a growth tendency when the Re number increases. Conversely, at low φ, the voltage and energy output decrease at higher Re number. The maximum voltage of 0.264 V is achieved when φ = 1.0 and Re = 1500, while the system delivers an energy output of 1.87 W.

Development of low-cost micro-fabrication procedures for planar micro-thermoelectric generators based on thin-film technology for energy harvesting applications.

With the rapid proliferation of portable and wearable electronics, energy autonomy through efficient energy harvesting has become paramount. Thermoelectric generators (TEGs) stand out as promising candidates due to their silent operation, high reliability, and maintenance-free nature. This paper presents the design, fabrication, and analysis of a micro-scale TEG for powering such devices. A planar configuration was employed for its inherent miniaturization advantages. Finite element analysis using ANSYS reveals that a double-layer device under a 50 K temperature gradient generates an impressive open-circuit voltage of 1417 mV and a power output of 2.4 μW, significantly exceeding its single-layer counterpart (226 mV, 0.12 μW). Validation against the analytical model results yields errors within 2.44% and 2.03% for voltage and power, respectively. Furthermore, a single-layer prototype fabricated using paper shadow masks and sputtering deposition exhibits a voltage of 131 mV for a 50 K temperature difference, thus confirming the feasibility of the proposed design. This work establishes a foundation for developing highly efficient micro-TEGs for powering next-generation portable and wearable electronics.

Self-Powered Temperature Electronic Skin Based on Island-Bridge Structure and Bi-Te Micro-Thermoelectric Generator for Distributed Mini-Region Sensing.

Thermoelectric (TE) effect based temperature sensor can accurately convert temperature signal into voltage without external power supply, which have great application prospects in self-powered temperature electronic skin (STES). But the fabrication of stretchable and distributed STES still remains a challenge. Here, a novel STES design strategy is proposed by combining flexible island-bridge structure with BiTe-based micro-thermoelectric generator (µ-TEG). Furthermore, a 4×4 vertical temperature sensor array with good stretchability and distributed sensing property has been fabricated for the first time. The interfacial chemical bonds located between the rigid islands (µ-TEG) and the flexible substrate (polydimethylsiloxane, PDMS) endow the STES with excellent stretchability, and its sensing performance remains unchanged under 30% strain (the maximum strain of human skin). Moreover, the STES sensing unit possesses high sensitivity (729 µV K-1 ), rapid response time (0.157 s), and high spatial resolution (2.75×2.75 mm2 ). As a proof of concept, this work demonstrates the application of the STES in the detection of mini-region heat sources in various scenarios including noncontact spatial temperature responsing, intelligent robotic thermosensing, and wearable temperature sensing. Such an inspiring design strategy is expected to provide guidance for the design and fabrication of wearable self-powered temperature sensors.

Composite energy acquisition of thermal and kinetic energy from cetaceans based on micro thermoelectric generator and triboelectric nanogenerator

Mobile marine environment sensor plays an essential role in the area of assessment of marine environments. However, the power supply duration of the mobile devices is facing significant challenges that need to be addressed. In this study, a self-powered systemformarine environmental sensors basedoncetaceans (SMES) is developed using a micro thermoelectric generator (MTEG) and a triboelectric nanogenerator (TENG). The SMES is designed for the mobile marine environment monitoring device with cetaceans as the carrier. The system can convert the thermal and kinetic energy of cetaceans into electrical energy and store it in a battery. A theoretical model is established using the correlation involving the frequency and amplitude of cetaceans and the output voltage of MTEG. The influence of the dynamic and kinematic characteristics of cetaceans on the performance of MTEG and TENG is studied. The UOC,max of Fishtailing-TENG is 5.85 V and the UOC,max of MTEG is 1.821 V. Therefore, the system enables the marine environment monitoring device to obtain accurate and valuable scientific data on the marine environment in a wider range of marine areas.

High Thermoelectric Performance of Non-Stoichiometric and Oriented GeTe Thin Films.

The increasing demand for micro-thermoelectric coolers and generators promotes the research on thermoelectric (TE) thin films. As a promising medium-temperature TE material, GeTe has attracted wide attention recently. However, the thermoelectric performance of thin-film GeTe remains inferior. Herein, oriented GeTe films with excessive Ge are obtained by magnetron co-sputtering technique, which can not only reduce the carrier concentration but also increase the carrier mobility, maintaining the high electrical conductivity of GeTe. Furthermore, higher structural symmetry and grain boundary scattering enhance the Seebeck coefficient of oriented GeTe films. As a result, the power factor (PF) value can reach as high as 2848 µW m-1 K-2 at room temperature and increase to 5263 µW m-1 K-2 at 600 K. Furthermore, a TE device with the Ge-rich GeTe thin film is fabricated and the maximum output power density (power per unit area) reaches 0.3W cm-2 at ΔT = 250 K. This work demonstrates that the stoichiometry and orientation modulations are effective strategies to improve the thermoelectric performance of GeTe thin films.

A Novel Thermal Tactile Sensor Based on Micro Thermoelectric Generator for Underwater Flow Direction Perception

Underwater vehicles can operate independently in the exploitation of marine resources. However, water flow disturbance is one of the challenges underwater vehicles must face. The underwater flow direction sensing method is a feasible way to overcome the challenges but faces difficulties such as integrating the existing sensors with underwater vehicles and high-cost maintenance fees. In this research, an underwater flow direction sensing method based on the thermal tactility of the micro thermoelectric generator (MTEG) is proposed, with the theoretical model established. To verify the model, a flow direction sensing prototype is fabricated to carry out experiments under three typical working conditions. The three typical flow direction conditions are: condition No. 1, in which the flow direction is parallel to the x-axis; condition No. 2, in which the flow direction is at an angle of 45° to the x-axis; and condition No. 3, which is a variable flow direction condition based on condition No. 1 and condition No. 2. According to the experimental data, the variations and orders of the prototype output voltages under three conditions fit the theoretical model, which means the prototype can identify the flow direction of three conditions. Besides, experimental data show that in the flow velocity range of 0~5 m/s and the flow direction variation range of 0~90°, the prototype can accurately identify the flow direction in 0~2 s. The first time utilizing MTEG on underwater flow direction perception, the underwater flow direction sensing method proposed in this research is cheaper and easier to be applied on the underwater vehicles than traditional underwater flow direction sensing methods, which means it has great application prospects in underwater vehicles. Besides, the MTEG can utilize the waste heat of the underwater vehicle battery as the energy source to achieve self-powered work, which greatly enhances its practical value.

Optimal Design of Wearable Micro Thermoelectric Generator Working in a Height-Confined Space

With the increasing development of self-powered wearable electronic devices, there is a growing interest in thermoelectric generators (TEGs). To achieve more comprehensive and reliable functionality of wearable devices, improving the power generation performance of thermoelectric devices will be the key. It has been shown that integrating a heat sink at the cold end of the TEG increases the effective temperature difference and, thus, maximizes the power output of the thermoelectric device. However, the space left for the power supply is often limited. How to optimize the integrated system of micro-thermoelectric generators and heat sinks in a height-confined space has become the key. In this study, we have established a corresponding model using a numerical calculation method, systematically studied the influence of TEG geometric size on the number of fins and fin height, and determined the optimal number of fins for the highest equivalent convective heat transfer coefficient corresponding to different fin heights. We also conducted the co-design of TEG and fin topological structure to study the effects of the ratio of leg height to fin height (l/H), the width of legs (w), and the number of thermoelectric leg pairs (N) on the maximum output power density per unit area (Pm1) and the maximum output power density per unit mass (Pm2) of the device. When N = 16, w = 0.3 mm, l/H = 2.5 (that is, l = 3.57 mm, H = 1.43 mm), and Pm1 reaches the maximum value of 30.5 μW/cm2; When N = 2, l/H = 0.25 and w = 0.3 mm, and Pm2 reaches a maximum value of 5.12 mW/g. The measured values of the open-circuit voltages of fabricated micro-TEGs with different thermoelectric leg heights (l = 0.49 mm, l = 1.38 mm, and l = 1.88 mm) are basically consistent with the simulated values. When N = 2, l = 0.49 mm, H = 3.74 mm, and w = 0.85 mm, and Pm2 reaches 0.44 mW/g. The results provide insights into the optimal design of wearable micro thermoelectric generator working in a height-confined space and highlight the importance of co-designing TEGs and fin topological structures for optimizing their performance.

Superior Thermoelectric Performance of SiGe Nanowires Epitaxially Integrated into Thermal Micro-Harvesters.

Semiconductor nanowires have demonstrated fascinating properties with applications in a wide range of fields, including energy and information technologies. Particularly, increasing attention has focused on SiGe nanowires for applications in a thermoelectric generation. In this work, a bottom-up vapour-liquid-solid chemical vapour Deposition methodology is employed to integrate heavily boron-doped SiGe nanowires on thermoelectric generators. Thermoelectrical properties -, i.e., electrical and thermal conductivities and Seebeck coefficient - of grown nanowires are fully characterized at temperatures ranging from 300 to 600 K, allowing the complete determination of the Figure-of-merit, zT, with obtained values of 0.4 at 600 K for optimally doped nanowires. A correlation between doping level, thermoelectric performance, and elemental distribution is established employing advanced elemental mapping (synchrotron-based nano-X-ray fluorescence). Moreover, the operation of p-doped SiGe NWs integrated into silicon micromachined thermoelectrical generators is shown over standalone and series- and parallel-connected arrays. Maximum open circuit voltage of 13.8mV and power output as high as 15.6 µW cm-2 are reached in series and parallel configurations, respectively, operating upon thermal gradients generated with hot sources at 200 °C and air flows of 1.5 m s-1 . These results pave the way for direct application of SiGe nanowire-based micro-thermoelectric generators in the field of the Internet of Things.

Investigation of CH4 and porous media addition on thermal and working performance in premixed H2/air combustion for micro thermophotovoltaic

Primary obstacles to the development of micro-thermoelectric generators are the gigantic heat loss ratio and flame instability. Premixed H2/air combustion in the micro-planar combustor with porous media (PM) and CH4 blended is experimentally and numerically conducted to boost the generator working performance. Effects of porosities, PM length and CH4 blending on combustion characteristics and thermal performance are detailedly studied at various operating conditions. Results indicate that flame stability is enhanced in PM, and the burner radiation temperature is also significantly boosted because of heat recirculation and heat transmission from flame. PM porosity ε = 0.9 balances the effects of solid skeleton on flame propagation and thermal improvement, which is conducive to flame stabilization. The coupling of PM setting and 25 % CH4 blending strongly improves the combustor thermal performance via altering the flame location and enhancing heat transmission. It also ameliorates the uniformity of radiation wall. Moreover, prolonging porous matrix has a positive effect on the improvement of thermal performance under a high chemical energy input. Particularly, combustor #C-Ls13 obtains an electrical output of 2.5 W and a system efficiency of 2.1 % at 25 %CH4-75 %H2 fueled combustion.

Unlocking microwatt power: enhanced performance of Fe–V–Al thin films in thermoelectric microgenerators

Microwatt power output obtained in thermoelectric microgenerators based on cost-effective and non-toxic Fe–V–Al thin films deposited by a DC magnetron co-sputtering process.

Metal-based folded-thermopile for 2.5D micro-thermoelectric generators

Metal-based folded-thermopile for 2.5D micro-thermoelectric generators

Underwater hybrid energy harvesting based on TENG-MTEG for self-powered marine mammal condition monitoring system

To effectively protect endangered marine mammals, one needs to collect and monitor their biological data and living environment information. This is however a great challenge for the endurance of marine mammal condition monitoring devices. The present study is to propose a self-powered marine mammal condition monitoring system, based on the hybrid energy harvesting mode of triboelectric nanogenerator (TENG) and micro thermoelectric generator (MTEG), to address the challenge. This system not only can obtain energy from the movement of marine mammals but also harvest energy from the temperature difference between the body surface and the ambient. The system fittingly integrates oscillating-TENG (O-TENG), MTEG, and power management unit. Note that O-TENG and MTEG can produce the maximal open circuit voltages of 5.85 V and 1.821 V, respectively. The TENG + MTEG hybrid energy harvesting device can improve the energy collection and battery charging performance by 4.93% compared with the MTEG single energy acquisition device. Hence, it can prolong the service life of the device, achieve an excellent stability, and is easy to manufacture. Eventually, the system can provide an effective and long-term endurance strategy for the condition monitoring device of endangered marine mammals.

Design and Application of a New Self-Powered Sensing Device Based on MTEG and FTENG

In recent years, the increasing demand for the establishment of smart ocean systems has promoted the exploration of self-powered sensing devices. However, a traditional battery has the disadvantages of limited energy storage and frequent replacement. These disadvantages make it difficult to power electronic equipment for a long time, which has become a major obstacle to constructing smart ocean systems. To meet these challenges, a new self-powered sensing device based on a microthermoelectric generator (MTEG) and flag-type triboelectric nanogenerator (FTENG) is proposed. The prototype is a hybrid energy-harvesting system. Through this prototype, solar and wind energy can be harvested simultaneously, and it can be employed to continuously power environmental sensors. In addition, the performance of the prototype was tested. Under the condition of a hot end at 70°C and a wind speed of 10 m/s, the prototype can charge the supercapacitor to 5.5 V in 10 min. Additionally, the prototype can sense and transmit wind speed and direction data. This research provides a new way for the establishment of smart ocean systems.