Circuit Conditions Research Articles

Comparative Investigation of Comparative Investigation of Triboelectric Energy Harvesting Modes: A Simulation Study Energy Harvesting Modes: A Simulation Study

This study presents a comparative analysis focused on simulating the operational modes of a triboelectric nanogenerator (TENG) using simulation-based method. Simulation modeling was performed using a demo version of the Comsol Multiphysics software. The simulations were conducted under both open circuit and short circuit conditions. The study provides the voltages across the surface of the electrodes under open circuit conditions and the transferred electrical charges under short circuit conditions, along with their respective graphs. The study examines the four main operating modes of a TENG—Vertical Contact-Separation Mode, Lateral Sliding Mode, Single-Electrode Mode, and Freestanding Mode—simulated under specific parameter sets. These results hold significant importance in the design stage of a Triboelectric Nanogenerator (TENG), as each working mode necessitates a specific interface circuit to harvest energy efficiently. Therefore, the evaluation of the findings of this study can be instrumental in the design optimization of TENG structures.

Plasma displacement calculation for TT-1 device based on multiple magnetic probes fitting methods

The HT-6M device has been upgraded and rebranded as the Thailand Tokamak 1 (TT-1), which has been reinstalled and is now operational in Thailand. In tokamak discharge experiments, precise monitoring of plasma position and the implementation of effective feedback control are essential for ensuring the stability of the high-temperature plasma. Accurate calculation of plasma displacement is critical to the success of the experiment. This paper presents a method for calculating plasma displacement through a multi-probe fitting technique, utilizing data from twelve magnetic field probes. Initially, magnetic field signals generated by the plasma are collected via multiple magnetic field probes installed poloidally outside the vacuum chamber, coupled with corresponding signal conditioning and integration circuits, with each probe undergoing calibration. Subsequently, during tokamak discharges, interference signals from the toroidal field coils, ohmic heating coils, and vertical field coils are generated by the magnetic system and corrected through a detailed calibration process. Lastly, the distances between the probes and the plasma are computed using data from the magnetic field probes, which are arranged in a circular configuration. The least squares method is employed to formulate a residual equation for fitting the actual plasma displacement. The effectiveness of this approach was validated through experimental data from the TT-1 device, demonstrating that the calculated plasma displacement exhibits a consistent trend with the CCD video recordings. This multi-probe displacement calculation method enables precise control of plasma displacement, thereby providing theoretical support for tokamak experiments and establishing a foundation for future experimental operations and data analysis.

Long term porosity of solid electrolyte interphase on model silicon anodes with liquid battery electrolytes

A stable solid electrolyte interphase (SEI) is of great importance for battery electrodes in terms of cycling as well as for its shelf life. While SEI formation on silicon anodes is generally only studied after the first charge and discharge of cells and initial reaction of electrolyte, we show the formation of a liquid/solid SEI in symmetric cells with silicon electrodes in contact with carbonate and glyme-based electrolytes under close to open circuit conditions and its behavior during long-term ageing. Activation energies of SEIs were measured via temperature-dependent electrochemical impedance spectroscopy (EIS) to study the contribution of liquid/solid phases to ion transport. The effect of different solvents, salts, their concentrations, and final water content of the glyme-electrolyte on the SEI was studied in detail. SEIs formed in cells with glyme-based electrolytes are generally more porous than the ones in cells with carbonate-based electrolytes. The addition of vinylene carbonate to glyme electrolyte is shown to be beneficial for its SEI, as it causes lower and more stable SEI resistances over time. A small amount of water in glyme electrolytes causes a denser SEI without much change in SEI resistance.

Electrochromic windows and flexible devices based on viologen-containing hydrogel electrolytes

Electrochromic devices (ECDs) with reversible optical modulation have great potential for smart window and flexible device applications. In this study, we propose low-power consumption, all-in-one-type ECDs based on LiCl-containing polyacrylamide (PAAm) hydrogel as a transparent and flexible gel electrolyte. Hydrophilic 1,1′-bis(3-hydroxypropyl) viologen dibromide (V-OHP) was served as the electrochromic (EC) material, hydroquinone (H2Q) was used as the anodic species, and H2Q/V-OHP/LiCl molar ratio was adjusted to obtain a balanced charge for the desired redox states of V-OHP. The basis for using V-OHP is derived from its hydroxyl groups, which enhance the hydrophilic characteristics of the radical cation (V-OHP*) and, as a result, the stability of the colored radical cations. This leads to enhanced stability, longer cycle life, and improved device dynamics. Investigations were also conducted into the EC behavior of viologen in solution. Following the utilization of various ECDs with various ratios of LiCl and H2Q, the most optimal sample was chosen and its efficiency in the application of EC windows and flexible devices was assessed. The created EC windows demonstrated distinct features including a significant contrast, outstanding stability, and a substantial cycle life (preserving over 94 % of the original transmittance after 800 cycles). Distinct device dynamics were also evident at a voltage of − 1.4 V with a time constant of about 10 s for coloring and 33 s for bleaching in open circuit condition.

Interpretation of Impedance Spectra for Neural Stimulation Devices in Vitro

The interpretation of the physical properties of any given electrode device requires precise models for analyzing the impedance spectroscopy data and assessment of the data consistency with the Kramers-Kronig relations. In 1992, Shannon [1] studied the influence of charge reactions and charge density on macro electrodes and proposed safe levels of electrical stimulation for macro electrodes employed in brain stimulation. However, the current density performance of neural stimulation devices is dependent on the electrode size. By considering the contributions of both charging and faradaic current densities on the impedance spectroscopy data for microelectrode and ultra-microelectrode devices, we aim to develop accurate models and provide reliable data interpretation for the physical properties of neural stimulation devices.We conducted electrochemical impedance spectroscopy (EIS) measurement for our 32-channel ultramicroelectrode device with site diameters ranging from 5 microns to 10 microns. The experiment was performed with the Gamry Reference 600+ Potentiostat, at open circuit conditions. The three-electrode-cell configuration consists of the working electrode, an Ag/AgCl reference, and a Platinum mesh counter electrode, immersed in phosphate-buffered saline. Impedance measurements were collected at an applied AC voltage of 25 mV rms with a frequency sweep from 10 kHz to 0.2 Hz at 10 points per decade.The limits of the EIS measurements were assessed by plotting the accuracy contour plot for the Gamry Reference 600+ Potentiostat and the Reference 600+ Potentiostat connected to the 32-channel ultramicroelectrode device by a junction box. Methods for assessing potentiostat limits followed Gamry's recommendations, including open and shorted lead EIS measurements [2]. The accuracy of impedance measurement for the ultramicroelectrode device was evaluated using loops and terminal features on the device that enabled closed-circuit and open-circuit measurements, respectively.The EIS data for the smaller electrodes (with diameters of 10 microns and 5 microns) were influenced by the capacitance of the cables; whereas, the larger/reference electrode (with an area of 4004 square microns) was unaffected by cable capacitance but was affected by ohmic impedance. The impedance spectra of the ultramicroelectrode device were regressed with a measurement model program [3] to compute the stochastic error structure and obtain parameters for accurate interpretation of the electrodes’ properties. Most of the data was consistent with the Kramers-Kronig relations.The circuit element for the parasitic capacitance was added to the process model to fit the data points affected by the cable capacitance at high frequency. At open circuit, the model accounted for the constant element behavior of the electrode, and mass-transfer influenced by oxygen-reduction reactions. The capacitance of the electrodes was estimated by the application of Brug’s formula to the fitting parameters obtained from the process model analysis and the measurement model regression results. The capacitance calculated with the measurement model was consistent with the values of the parasitic capacitance obtained from the process model regression analysis.

Multiplex Pulsed Current Sensors for Anion Detection

Low-cost and stable sensors are needed for long-duration monitoring of nitrate and phosphate in waterways to help improve farming practices and understand the negative environmental and economic impacts caused by the release of these ions. One established platform that shows promise for detecting these ions is the use of solid-contact ion selective electrodes (SC−ISEs). Conventional SC-ISE measurements monitor electrode potential under open circuit conditions to quantify the amount of one target analyte. These conventional SC-ISEs rely on highly engineered membrane materials that are formulated to selectively bind to the target ion. These engineered membrane materials can achieve high selectivity for nitrate and phosphate, but are vulnerable to certain interferents, require frequent calibration, and have poor long-term stability. In recent work, we demonstrated the use of pulsed current technique for anion detection in SC-ISEs, which allows for anion detection based on differences in anion diffusion through the membrane rather than selective anion binding – opening up a wide range of materials as candidates for ion sensing membranes. In this report, we employ pulsed current measurement to examine anion detection using three common polymers as membrane layers: polyvinyl acetate (PVA), polyvinylchloride (PVC), and polyacrylonitrile (PAN). We measure the potential vs. time response for these three membrane materials in solutions containing various anions such as nitrate, phosphate, chloride, and carbonate at varying pulse currents. Afterwards, we employ tree-based and neural-based machine learning algorithms to examine the feasibility of detecting multiple ions simultaneously using the combined response data from multiple electrodes. Our experiments illustrate that our method for anion detection, used with machine learning analysis, is useful for investigating the interaction mechanisms of anions with the polymer matrix.

(Invited) Progress in the Analytical Capability of X-Rays to Locate Chemical Phenomena in Battery Materials

The evolution of local chemistry determines the performance of electrodes and electrolytes used in batteries because limitations can be tracked to slow kinetics and transport, and irreversibilities in the storage reaction. Tools that provide insight into local chemistry are critical for identifying the underpinnings of electrochemical function. This information must be resolved within architectures, from individual particles to microscale domains, to pinpoint the relationship between local phenomena and their role in macroscopic metrics and degradation. Technical developments in X-ray microscopy and mapping have built a flexible suite of tools that combine the desired spatial resolution and 3D capabilities with a suite of possible contrasts mechanisms, such as diffraction and spectroscopy. In this talk, we will discuss our recent research that demonstrates the diversity of length scales at which important chemical heterogeneity can be induced in battery electrodes. For this purpose, the systems of study will be the leading cathodes for Li-ion batteries. We will highlight the new fundamental insight generated by the tools, but also motivate the need for the extension of the analytical capabilities of the tools into outcomes of high statistical significance. The insight generated by our approaches will be related to their impact on material and architecture properties. Along the way, we will also provide a glimpse into the future by showing how emerging synchrotron techniques can enhance the impact of X-ray microscopy in fundamental battery science. Particularly, we will discuss the prospects of probing time-resolved phenomena using operando measurements to avoid uncertainty due to relaxation under open circuit conditions.

Conflict during learning reconfigures the neural representation of positive valence and approach behavior

Punishing and rewarding experiences can change the valence of sensory stimuli and guide animal behavior in opposite directions, resulting in avoidance or approach. Often, however, a stimulus is encountered with both positive and negative experiences. How is such conflicting information represented in the brain and resolved into a behavioral decision? We address this question by dissecting a circuit for sexual conditioning in C.elegans. In this learning paradigm, an odor is conditioned with both a punishment (starvation) and a reward (mates), resulting in odor approach. We find that negative and positive experiences are both encoded by the neuropeptide pigment dispersing factor 1 (PDF-1) being released from, and acting on, different neurons. Each experience creates a distinct memory in the circuit for odor processing. This results in the sensorimotor representation of the odor being different in naive and sexually conditioned animals, despite both displaying approach. Our results reveal that the positive valence of a stimulus is not represented in the activity of any single neuron class but flexibly represented within the circuit according to the experiences and predictions associated with the stimulus.

Stabilization of High‐Valent Molecular Cobalt Sites through Oxidized Phosphorus in Reduced Graphene Oxide for Enhanced Oxygen Evolution Catalysis

AbstractHeterogeneous molecular cobalt (Co) sites represent one type of classical catalytic sites for electrochemical oxygen evolution reaction (OER) in alkaline solutions. There are dynamic equilibriums between Co2+, Co3+ and Co4+ states coupling with OH−/H+ interaction before and during the OER event. Since the emergence of Co2+ sites is detrimental to the OER cycle, the stabilization of high‐valent Co sites to shift away from the equilibrium becomes critical and is proposed as a new strategy to enhance OER. Herein, phosphorus (P) atoms were doped into reduced graphene oxide to link molecular Co2+ acetylacetonate toward synthesizing a novel heterogeneous molecular catalyst. By increasing the oxidation states of P heteroatoms, the linked Co sites were spontaneously oxidized from 2+ to 3+ states in a KOH solution through OH− ions coupling at an open circuit condition. With excluding the Co2+ sites, the as‐derived Co sites with 3+ initial states exhibited intrinsically high OER activity, validating the effectiveness of the strategy of stabilizing high valence Co sites.

Deep learning-based system for measuring weak electrical signals in plants

Abstract Due to the characteristics of plant electrical signals being weak, low-frequency, and susceptible to interference, this study proposes a hardware solution involving silver chloride medical adhesive electrodes and the design of conditioning circuits to amplify the plant electrical signals and reduce noise. On the software side, deep learning algorithms are proposed to extract the voltage values from a self-built plant electrical signal acquisition system. Experiments were conducted on two aloe vera plants grown in different environments. Voltage signals were synchronously collected by using a high-precision digital multimeter with anti-interference capabilities. The measured signals from the system were used as input signals for a 1D-CNN, and the synchronized high-precision digital multimeter measurements served as network labels. The 1D-CNN network was then trained by using deep learning algorithms to fit the voltage values from the acquisition system to those of the high-precision digital multimeter. This approach effectively reduces noise and extracts accurate voltage values in the self-built measurement system. By combining hardware and software, the precision of the measurements is improved, providing a new method for measuring plant electrical signals.

Sound transmission characteristics of piezoelectric metamaterial plates with resonant shunt circuits

Abstract In this study, a comprehensive investigation is conducted into the sound transmission characteristics of piezoelectric metamaterial plates, which feature five distinct resonant shunt circuits. To begin with, the intrinsic equations that pertain to piezoelectric materials, along with their equivalent models under external circuit conditions are established. Subsequently, the sound transmission loss of the plate and its corresponding equivalent bending stiffness model are constructed. Five resonant shunt circuits are employed, encompassing a basic resonant shunt circuit, one with series/parallel capacitance, and another with series/parallel negative capacitance. Ultimately, the influence of these diverse shunt circuits and their respective parameters on the sound insulation capabilities of piezoelectric metamaterial plates is comprehensively calculated and analyzed. Research results show that the inductance and resistance within the resonant shunt circuit influence the sound transmission characteristics exhibited by the piezoelectric metamaterial plate. Irrespective of whether the capacitance is configured in parallel or series within the resonant shunt circuit, the low-frequency sound transmission loss of the piezoelectric metamaterial plate experiences a notable modification. The effect of negative capacitances in the resonant shunt circuit on the sound transmission loss of the plate exhibits a contrasting pattern compared to the influence of the capacitances within the resonant shunt circuit on the sound transmission loss.

Evaluation of extra-corporeal membrane oxygenator cannulae in pulsatile and non-pulsatile pediatric mock circuits.

This study evaluated the hemodynamic performance of arterial and venous cannulae in a compliant pediatric extracorporeal membrane oxygenation (ECMO) mock circuit in pulsatile and non-pulsatile flow conditions. The ECMO setup consisted of an oxygenator, diagonal pump, and standardized-length arterial/venous tubing with pressure transducers. A validated left-heart mock loop was adapted to simulate pediatric conditions. The pulsatile flow was driven by a computer-controlled piston pump set at 120 bpm. A roller pump was used for non-pulsatile conditions. The circuit was primed with 40% glycerol-based solution. The cardiac output was set to 1 L/min and the aortic pressure to 40-50 mmHg. Four arterial cannulae (8Fr, 10Fr, 12Fr, 14Fr) and five venous cannulae (12Fr, 14Fr, 16Fr, 18Fr, 20Fr) (Medtronic, Inc., Minneapolis, MN, USA) were tested at increasing flow rate in 12 combinations. The pulsatile condition required lower ECMO pump speeds for all cannulae combinations at a given flow rate, inducing a significantly smaller increase of flow in the mock loop. Under non-pulsatile conditions, the aortic and arterial pressures in the cannulae were higher (p < 0.01) while no significant differences in pressure drop and pressure-flow characteristics (M-number) were observed. The total hemodynamic energy was higher in case of non-pulsatile flow (p < 0.01). Under non-pulsatile conditions, the system was characterized by overall higher pressures, resulting in higher support to the patient. The consequent increase of potential energy compensates for increases of kinetic energy, leading to a higher total hemodynamic energy. Pressure gradients and M number are independent of the testing conditions. Pulsatile testing conditions led to more physiological testing conditions, and it is recommended for ECMO testing.

A Self-Powered Wireless Temperature Sensor Platform for Foot Ulceration Monitoring.

This work describes a self-powered wireless temperature sensor platform that can be used for foot ulceration monitoring for diabetic patients. The proposed self-powered sensor platform consists of a piezoelectric bimorph, a power conditioning circuit, a temperature sensor readout circuit, and a wireless module. The piezoelectric bimorph mounted inside the shoe effectively converts the foot movement into electric energy that can power the entire sensor platform. Furthermore, a sensor platform was designed, considering the energy requirement of 4.826 mJ for transmitting one data packet of 18 bytes. The self-powered sensor platform prototype was evaluated with five test subjects with different weights and foot shapes; the test results show the subjects had to walk an average of 119.6 s to transmit the first data packet and an additional average of 71.2 s to transmit the subsequent data packet. The temperature sensor showed a resolution of 0.1 °C and a sensitivity of 56.7 mV/°C with a power conditioning circuit efficiency of 74.5%.

Microbial symbiotic electrobioconversion of carbon dioxide to biopolymer (poly (3-hydroxybutyrate)) via single-step microbial electrosynthesis cell

This study proposes an novel single-stage microbial electrosynthesis system (MES) that bioelectrochemically converts CO2 into poly(3-hydroxybutyrate) (PHB). This innovative approach utilizes a symbiotic co-culture of electroactive acetogenic bacteria and PHB-accumulating bacteria within a single reactor, bypassing the need for separate acetate production and extraction. Systematic optimization of key operational parameters, including applied voltage, carbon source, and cathode material, was conducted to maximize PHB production. Results demonstrate that using a voltage of 2.5 V yielded a 7.14-fold increase in PHB content compared to open circuit conditions. Furthermore, functionalizing the cathode with a conductive and hydrophilic PEDOT: PSS polymer coating significantly enhanced the system’s performance, resulting in a 1.5-fold increase in both acetate and PHB production compared to unmodified carbon felt electrodes. The long-term stability and effectiveness of the co-culture system were validated through comprehensive microbial and metagenomic analyses. Results revealed a significant enrichment of CO2-utilizing electrotrophs within the cathode biofilm, including Acetobacterium and Clostridium. Concurrently, a 4 to 14-fold increase in the relative abundance of PHB-biosynthesizing bacteria, such as Pseudomonas, Rhodobacter and Caulobacter was observed in the planktonic phase. This study offers a promising pathway towards a circular bioeconomy by enabling the valorization of CO2 into valuable bio-based products via single-stage MES, utilizing a symbiotic co-culture.

Evaluation of imidazole blocking layers for perovskite stability

The prevention of AgI formation is critical for ensuring long term stability of perovskite solar cells. While sputtered metal oxide films are known for uniform dense film formation, solution phase nanoparticle coatings of metal oxides are prone to pinholes through which free iodide can migrate leading to AgI formation at the back contact. Iodide migration can be prevented through the addition of passivator or blocking layers at the perovskite/charge transport or charge transport/Ag interfaces. In this paper we evaluated a series of imidazoles as interfacial layers to prevent iodide migration from the perovskite to the Ag back contact through solution phase deposited Y:SnO2. We identified structural features of the imidazoles that contribute to an effective blocking layer. Specifically, it was found that imidazoles with conjugated planer systems and hydrogen bonding heteroatoms were able to prevent ion migration while retaining device performance. Of the materials evaluated 4-(Imidazol-1-yl)phenol had the best performance with a 60 % increase in stability verse the control under illumination at short circuit conditions.

Stabilization of High-Valent Molecular Cobalt Sites through Oxidized Phosphorus in Reduced Graphene Oxide for Enhanced Oxygen Evolution Catalysis.

Heterogeneous molecular cobalt (Co) sites represent one type of classical catalytic sites for electrochemical oxygen evolution reaction (OER) in alkaline solutions. There are dynamic equilibriums between Co2+, Co3+ and Co4+ states coupling with OH-/H+ interaction before and during the OER event. Since the emergence of Co2+ sites is detrimental to the OER cycle, the stabilization of high-valent Co sites to shift away from the equilibrium becomes critical and is proposed as a new strategy to enhance OER. Herein, phosphorus (P) atoms were doped into reduced graphene oxide to link molecular Co2+ acetylacetonate toward synthesizing a novel heterogeneous molecular catalyst. By increasing the oxidation states of P heteroatoms, the linked Co sites were spontaneously oxidized from 2+ to 3+ states in a KOH solution through OH- ions coupling at an open circuit condition. With excluding the Co2+ sites, the as-derived Co sites with 3+ initial states exhibited intrinsically high OER activity, validating the effectiveness of the strategy of stabilizing high valence Co sites.

Incorporation of Gold Nanoparticle into ZnO Electron Transport Layer to Improve Performance of Hybrid Bulk Heterojunction Solar Cell

Abstract We have investigated the effect of localized surface plasmon resonance (LSPR) from gold nanoparticles incorporated into the electron transport layer (ETL) of zinc oxide (ZnO) on charge carrier transport in order to improve the performance of inverted hybrid bulk-heterojunction solar cells. Synthesis of gold nanoparticles capped by 3-mercaptopropionic acid (AuMPA) and oleylamine (AuOA) was carried out by use of the reduction method and the fabrication of solar cell device with the configuration of ITO/ZnO:AuNPs/P3HT:PCBM/PEDOT:PSS/Ag was done by spin coating and thermal evaporation techniques. The absorbance spectra show a plasmonic peak of AuMPA in solution at 521 nm, while AuOA has a plasmonic peak at 531 nm, with both solutions showing a red-wine color. In our investigation, the incorporation of AuMPA about 2.65wt% or AuOA about 3.5 wt% in the ZnAc solution is quite stable. With the addition of 1.77 wt% AuMPA, the fabricated devices show a significant improvement at short circuit condition (JSC) from 46.67 mA/cm2 to 83.11 mA/cm2, resulting in an increase in power conversion efficiency (PCE) from 5.64% to 9.00% under the illumination of 100 mW/cm2 simulated solar irradiation. While the AuOA addition of 2.65 wt%, the JSC increased from 22.67 mA/cm2 to 44.12 mA/cm2 along with an improvement of PCE from 2.71% to 5.32%. The experiment results suggest that the electron mobility or charge carrier transport to the indium tin oxide (ITO) cathode is improved by the local electric field enhancement around the zinc oxide (ZnO) electron transport layer due to the effect of gold nanoparticles (AuNPs).

Stability and dissolution of single-crystalline iron oxide thin films in electrochemical environments

The stability of single-crystalline monolayer FeO(111) and 10 nm thin Fe3O4(111) films on Pt(111) upon exposure to environments of increasing chemical complexity has been studied with X-ray photoelectron spectroscopy, temperature-programmed desorption, in-situ scanning tunneling microscopy, and cyclic voltammetry. The well-defined oxide films, which were prepared under ultrahigh-vacuum conditions, were exposed to aqueous solutions of different pH and electrochemical cycling in pure and catechol-containing electrolyte. The films are stable in neutral (pH 7) and alkaline (pH 13) solutions both at open circuit conditions and during electrochemical cycling within the limits of hydrogen and oxygen evolution potentials. Also in strongly acidic (pH 1) perchlorate solution the films remain intact under open circuit conditions, but they quickly dissolve on application of electrochemical potential. Especially for the ultrathin FeO(111) films, catechol enhances the dissolution at neutral pH during electrochemical cycling. A comparison of Pt(111), FeO(111) and Fe3O4(111) substrates in the electrochemical catechol oxidation reaction reveals enhanced and sustained activity of FeO in alkaline environment, while strong deactivation occurs on Pt(111) and Fe3O4(111). This is explained by the weaker interaction between catechol and FeO(111) compared to the other substrates, which hampers the formation of a barrier layer on the electrode surface.

Development of a Compact NDIR CO2 Gas Sensor for a Portable Gas Analyzer

A carbon dioxide (CO2) gas sensor based on non-dispersive infrared (NDIR) technology has been developed and is suitable for use in portable devices for high-precision CO2 detection. The NDIR gas sensor comprises a MEMS infrared emitter, a MEMS thermopile detector with an integrated optical filter, and a compact gas cell with high optical coupling efficiency. A dual-ellipsoid mirror optical system was designed, and based on optical simulation analysis, the structure of the dual-ellipsoid reflective gas chamber was designed and optimized, achieving a coupling efficiency of up to 54%. Optical and thermal simulations were conducted to design the sensor structure, considering thermal management and light analysis. By optimizing the gas cell structure and conditioning circuit, we effectively reduced the sensor’s baseline noise, enhancing the overall reliability and stability of the system. The sensor’s dimensions were 20 mm × 10 mm × 4 mm (L × W × H), only 15% of the size of traditional NDIR gas sensors with equivalent detection resolution. The developed sensor offers high sensitivity and low noise, with a sensitivity of 15 μV/ppm, a detection limit of 90 ppm, and a resolution of 30 ppm. The total power consumption of the whole sensor system is 6.5 mW, with a maximum power consumption of only 90 mW.

Parameter effects on performance of piezoelectric wind energy harvesters based on the interaction between vortex-induced vibration and galloping

Our previous research experimentally validated that the interaction between vortex-induced vibration and galloping is an effective method for enhancing the performance of piezoelectric wind energy harvesters under low wind speed conditions. We proposed a distributed-parameter electromechanical coupling model as well. This study aims to investigate the effects of various parameters and optimize the performance of VIV-galloping interactive piezoelectric wind energy harvesters. Initially, we assessed the applicability of the model under different circuit and aerodynamic force conditions and discussed boundary and convergence conditions by replicating previous results. Further, simulations were performed to analyze the effects of the structural parameters of the bluff body and piezoelectric beam. The width or depth of the bluff body significantly influenced the low critical wind speed, interactive occurrence, and electrical output. To achieve a balance between material cost and electrical benefit, we recommend positioning the electrode length from the fixed end with a coverage ratio of at least 60%. Additionally, the output power is highly sensitive to the piezoelectric beam length, but reducing it results in a higher natural frequency and critical wind speed. We fabricated and tested four prototypes, which have demonstrated significantly higher power densities compared with previously reported values at the same wind speed.