Free-Standing Electrode and Fixed Surface Tiny Electrode Implemented Triboelectric Nanogenerator with High Instantaneous Current.

Conventional triboelectric nanogenerators (TENGs) face challenges pertaining to low output current density at low working frequencies and high internal impedance. While strategies, such as surface modification to enhance surface charge density, permittivity regulation of materials, and circuit management, have partially mitigated these issues. However, they have also resulted in increased complexity in the fabrication process. Therefore, there is an urgent demand for a universal and simplified approach to address these challenges. To fulfill this need, this work presents a free-standing electrode and fixed surface tiny electrode implemented triboelectric nanogenerator (FFI-TENG). It is fabricated by a straightforward yet effective method: introducing a tiny electrode onto the surface of the tribo-negative material. This approach yields substantial enhancements in performance, notably a more than tenfold increase in output current density, a reduction in effective working frequencies, and a decrease in matching resistance as compared to vertical contact-separation TENGs (CS-TENGs) or single-electrode TENGs (SE-TENGs). Simultaneously, a comprehensive examination and proposition regarding the operational mechanism of FFI-TENG, highlighting its extensive applicability are also offered. Significantly, FFI-TENG excels in mechanical energy harvesting even under ultra-low working frequencies (0.1 Hz), outperforming similar contact-separation models. This innovation positions it as a practical and efficient solution for the development of low-entropy energy harvesters.

Utilization of a TiO2-CuO Bimetallic/Polyaniline Nanocomposite as a Transducer in a Solid Contact Potentiometric Sensor for the Determination of Vildagliptin.

Current fundamental electrochemical research shows the potential of utilizing polymeric nanostructured materials as ion-to-electron transducers. In this paper, aniline was polymerized in the presence of TiO2 and CuO nanoparticles to yield a bimetallic/PANI nanocomposite. It was applied as a transducer in a carbon paste electrode for the potentiometric determination of vildagliptin in the presence of 18-crown-6-ether as a recognition element. The electrode's potentiometric performance was studied according to the IUPAC guidelines. It exhibited a wide linearity range of 1 × 10-2 M to 1 × 10-8 M, remarkable sensitivity (LOD of 4.5 × 10-9 M), and a fast response time of 10 s ± 1.3. The sensor did not show any potential drift due to the absence of the water layer between the carbon paste and the metallic conductor. This endowed the sensor with high stability and a long lifetime, as 137 days passed without the need to change the carbon paste surface. The electrode was utilized for the determination of the concentration of vildagliptin in bulk, pharmaceutical tablets, and human plasma, with average recovery ranging from 97.65% to 100.03%.

Controlled synthesis of van der Waals CoS2for improved p-type transistor contact.

Two-dimensional (2D) van der Waals (vdW) p-type semiconductors have shown attractive application prospects as atomically thin channels in electronic devices. However, the high Schottky hole barrier of p-type semiconductor-metal contacts induced by Fermi-level pinning is hardly removed. Herein, we prepare a vdW 1T-CoS2nanosheet as the contact electrode of a WSe2field-effect transistor (FET), which shows a considerably high on/off ratio > 107and a hole mobility of ∼114.5 cm2V-1s-1. The CoS2nanosheets exhibit metallic conductivity with thickness dependence, which surpasses most 2D transition metal dichalcogenide metals or semimetals. The excellent FET performance of the CoS2-contacted WSe2FET device can be attributed to the high work function of CoS2, which lowers the Schottky hole barrier. Our work provides an effective method for growing vdW CoS2and opens up more possibilities for the application of 2D p-type semiconductors in electronic devices.

Toward Personalized Treatment of Depression: An Affordable Citalopram Test based on a Solid-Contact Potentiometric Electrode for at-Home Monitoring of the Antidepressant Dosage.

Citalopram (CTLP) is one of the most common antidepressants prescribed worldwide. It has a narrow therapeutic window and can cause severe toxicity and mortality if the dosage exceeds the safe level. Reports indicated that at-home monitoring of citalopram dosage considerably benefits the patients, yet there are no devices capable of such measurement of citalopram in biofluids. This work presents an affordable citalopram test for at-home and point-of-care monitoring of citalopram levels in urine, ensuring a safe and effective drug compliance. Our platform consists of a citalopram-selective yarn-based electrode (CTLP-SYE) that uses polymeric sensing membranes to provide valuable information about drug concentration in urine. CTLP-SYE is noninvasive and has a response time of fewer than 10 s. The fabricated electrode showed near-Nernstian behavior with a 52.3 mV/decade slope in citalopram hydrobromide solutions ranging from 0.5 µM to 1.0 mM, with a detection limit of 0.2 µM. Results also indicated that neither interfering ions nor pH affects electrode performance. We showed that CTLP-SYE could accurately and reproducibly measure citalopram in human urine (RSD 2.0 to 3.2%, error <12%) at clinically relevant concentrations. This work paves the way for the personalized treatment of depression and accessible companion diagnostics to improve treatment efficacy and safety.

A Comparative Study between Screen-Printed and Solid-Contact Electrodes for the Stability-Indicating Determination of Bromazepam.

Stability-indicating methods are awesome tools to ensure the safety and efficacy of active pharmaceutical ingredients (APIs). An accurate comparative study involving the use of potentiometric sensors for the determination of bromazepam (BRZ) in the presence of its main product of degradation and impurity was performed by the fabrication of two membrane electrodes. A screen-printed electrode (SPE) and a solid-contact glassy carbon electrode (SCE) were fabricated and their performance optimized. The fabricated sensors showed a linear electrochemical response in the concentration range 1.0 × 10-6 M to 1.0 × 10-2 M. The electrodes exhibited Nernstian slopes of 59.70 mV/decade and 58.10 mV/decade for the BRZ-SPE and BRZ-SCE membrane electrodes, respectively. The electrochemical performance was greatly affected by the medium pH. They showed an almost ideal electrochemical performance between pH 3.0 and pH 6.0. The fabricated membranes were applied successfully for the quantification of BRZ in the presence of up to 90% of its degradation product. Moreover, a successful application of the fabricated electrodes was performed for the sensitive and selective quantification of BRZ in its tablet form without any pretreatment procedure.

Green potentiometric electrode for determination of salbutamol in biological samples.

Clinical drug analyses and identification of pharmaceuticals in biological samples are highly crucial for therapeutic drug monitoring, pharmacokinetic studies, and screening of illicit drugs. Various analytical tools, such as potentiometric electrodes, are used to conduct these investigations. These potentiometric electrodes are superior to other techniques in terms of greenness and cost efficacy, and thus present a good alternative for researchers. In this study, we develop an advanced electrode for the in-situ monitoring of salbutamol in plasma, this electrode was synthesized using multiwalled carbon nanotubes (MWCNT) as hydrophobic conductive substance and copper oxide nanoparticle (CuO NP) as a surface modifier, the developed electrode was compared to traditional liquid contact electrode as well as solid contact electrode and proved its superiority. The use of MWCNT improved the stability of the electrode via preventing the formation of this water layer and the CuO NP improved the sensitivity due to its high surface area and rich electronic properties. CuO NP modified electrode was used for the determination of salbutamol with a Nernstian slope of 57.4 over a linearity range of range 1.0 × 10-7- 1.0 × 10-2 M, and a detection limit of 4.0 × 10-7 M. The proposed electrode was effectively applied for the determination of the cited drug in rat plasma without interference and compared with chromatographic reported method. The proposed method is economic as it has a low sample analysis cost, time saving and needs fewer manipulation steps and a simple convenient device. It also proved to be a greener method when compared with chromatographic methods using an eco-scale metric system.

Flexible Non-contact Electrodes for Wearable Biosensors System on Electrocardiogram Monitoring in Motion.

Electrocardiogram (ECG) is a critical physiological indicator that contains abundant information about human heart activities. However, it is a kind of weak low-frequency signal, which is easy to be interfered by various noises. Therefore, wearable biosensors (WBS) technique is introduced to overcome this challenge. A flexible non-contact electrode is proposed for wearable biosensors (WBS) system, which is made up of flexible printed circuits materials, and can monitor the ECG signals during exercise for a long time. It uses the principle of capacitive coupling to obtain high-quality signals, and reduces the impact of external noise through active shielding; The results showed that the proposed non-contact electrode was equivalent to a medical wet electrode. The correlation coefficient was as high as 99.70 ± 0.30% when the subject was resting, while it was as high as 97.53 ± 1.80% during exercise. High-quality ECG could still be collected at subjects walking at 7 km/h. This study suggested that the proposed flexible non-contact electrode would be a potential tool for wearable biosensors for medical application on long-term monitoring of patients' health and provide athletes with physiological signal measurements.

Sacral Neuromodulation Using a Novel Device with a Six-contact-point Electrode for the Treatment of Patients with Refractory Overactive Bladder: A Multicenter, Randomized, Single-blind, Parallel-control Clinical Trial.

BACKGROUND: A novel sacral neuromodulation system (SacralStim) which has an electrode with six contact points was recently designed. OBJECTIVE: To evaluate the effectiveness and safety of the SacralStim system for treating patients with refractory overactive bladder (OAB). DESIGN, SETTING, AND PARTICIPANTS: This was a multicenter, randomized, single-blind clinical trial. Patients with refractory OAB were enrolled from January 2018 to May 2020. INTERVENTION: Participants were randomly allocated to the treatment group (SNM on) or the control group (SNM off) for a single-blind period of 12 ± 2 wk. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary outcome was the percentage of patients with a reduction in the average number of voids/24 h of at least 50% at the 12-wk follow-up visit. Other follow-up evaluations, including voiding diary outcomes, questionnaires on Overactive Bladder Symptom Score (OABSS), quality of life (QoL), device satisfaction, and causes of adverse events (AEs), were performed over the first 48 wk after implantation. RESULTS AND LIMITATIONS: The therapeutic success rate at 12 wk was 56.76% in the treatment group and 11.11% in the control group (p < 0.001). There were significant differences in voiding diary variables between the two groups, including changes in the average number of voids/24 h, micturition volume/void, and improvement in the urge incontinence ratio. No severe AEs occurred. A limitation is the sham stimulation used as a control in the study. A head-to-head study is required to make a direct comparison of devices with six and four contact points. CONCLUSIONS: This clinical trial provides strong evidence that patients with refractory OAB benefit from the novel SacralStim system. More research is required for direct comparison of the SacralStim system with traditional four-contact-point devices. PATIENT SUMMARY: This study confirms the effectiveness and safety of a novel SacralStim system that stimulates the sacral nerve for treatment of overactive bladder. The system has an electrode with six contact points and can provide more programming options after implantation.

Evaluation of sacral neuromodulation system with new six-contact points electrode in pigs.

AIMS: We investigated the effects of sacral neuromodulation using the new six-contact electrode vs the four-contact electrode in pigs. METHODS: Randomly, a six-contact electrode was implanted in eight pigs in one side of the third sacral (S3) foramen, and a four-contact electrode was implanted in the other side using the same method. Using an external neurostimulator, the number of contact points (sensitive voltage ≤ 2 V) of both electrodes (SacralStim and InterStim systems) was calculated. Cystometry was performed by infusing normal saline or acetic acid. Then sacral neuromodulation with the SacralStim and InterStim systems was induced at a voltage at which we could observe perianal and/or tail movement. Multiple cystometrograms were performed to determine the effects of the two systems on the micturition reflex. RESULTS: The mean number of sensitive points of six-contact electrodes of the SacralStim system (2.63 ± 0.32) was higher than that of the quadripolar-lead electrodes of the InterStim system (1.38 ± 0.18), and the difference was statistically significant (P < 0.05). Acetic acid-induced bladder overactivity significantly reduced bladder capacity to 54.89% ± 4.7% of the normal saline control level. During acetic acid infusion, sacral neuromodulation with the SacralStim system suppressed bladder overactivity and significantly increased bladder capacity to 70.41% ± 5.4% of the normal saline control level, compared with the acetic acid level ( P < 0.05). Moreover, sacral neuromodulation with the InterStim system also significantly increased bladder capacity to 69.63% ± 5.3% of the normal saline control level, compared with the acetic acid level ( P < 0.05). No significant differences were found in the results obtained using the two systems ( P > 0.05). CONCLUSIONS: The six-contact electrode of the SacralStim system had more sensitive points (<2 V) than that of the quadripolar-lead electrode of InterStim system. Potentially, it has more postimplantation programming options and battery savings manifested by lower voltage will increase the longevity of the stimulator. Further studies of sacral neuromodulation with six-contact electrodes in clinical practice are needed.

Metallic Vanadium Disulfide Nanosheets as a Platform Material for Multifunctional Electrode Applications.

Nanothick metallic transition metal dichalcogenides such as VS2 are essential building blocks for constructing next-generation electronic and energy-storage applications, as well as for exploring unique physical issues associated with the dimensionality effect. However, such two-dimensional (2D) layered materials have yet to be achieved through either mechanical exfoliation or bottom-up synthesis. Herein, we report a facile chemical vapor deposition route for direct production of crystalline VS2 nanosheets with sub-10 nm thicknesses and domain sizes of tens of micrometers. The obtained nanosheets feature spontaneous superlattice periodicities and excellent electrical conductivities (∼3 × 103 S cm-1), which has enabled a variety of applications such as contact electrodes for monolayer MoS2 with contact resistances of ∼1/4 to that of Ni/Au metals, and as supercapacitor electrodes in aqueous electrolytes showing specific capacitances as high as 8.6 × 102 F g-1. This work provides fresh insights into the delicate structure-property relationship and the broad application prospects of such metallic 2D materials.

Design of Contact Electrodes for Semiconductor Nanowire Solar Energy Harvesting Devices.

Transparent, low-resistive contacts are critical for efficient solar energy harvesting devices. It is important to reconsider the material choices and electrode design as devices move from 2D films to 1D nanostructures. In this paper, we study the effectiveness of indium tin oxide (ITO) and metals, such as Ag and Cu, as contacts in 2D and 1D systems. Although ITO has been studied extensively and developed into an effective transparent contact for 2D devices, our results show that effectiveness does not translate to 1D systems. Particularly with consideration of resistance requirement, nanowires with metal shells as contacts enable better absorption within the semiconductor as compared to ITO. Furthermore, there is a strong dependence of contact performance on the semiconductor band gap and diameter of nanowires. We found that metal contacts outperform ITO for nanowire devices, regardless of the sheet resistance constraint, in the regime of diameters less than 100 nm and band-gaps greater than 1 eV. These metal shells optimized for best absorption are significantly thinner than ITO, which enables for the design of devices with high nanowire number density and consequently higher device efficiencies.

[Development of the Non-contact ECG Electrode].

We designed a non-contact electrode on the basis of the capacitance coupling principle, it can be used for physiological signal acquisition, it uses dynamic shielding and electrode active driving technology to improve the quality of the signal. Experiments use this electrode to structure the ECG signal acquisition system, the ECG signal were collected with non-contact electrodes, comparing with traditional wet electrodes, the results show that noncontact electrodes developed in this paper can effectively meet the needs of ECG signal acquisition.

Benchmarking electrical methods for rapid estimation of root biomass.

BACKGROUND: To face climate change and subsequent rainfall instabilities, crop breeding strategies now include root traits phenotyping. Rapid estimation of root traits in controlled conditions can be achieved by using parallel electrical capacitance and its linear correlation with root dry mass. The aim of the present study was to improve robustness and efficiency of methods based on capacitance and other electrical variables, such as serial/parallel resistance, conductance, impedance or reactance. Using different electrode configurations and stem contact electrodes, we have measured the electrical impedance spectra of wheat plants grown in pots filled with three types of soil. RESULTS: For each configuration, parallel capacitance and other linearly independent electrical variables were computed and their quality as root dry mass estimator was evaluated by a 'sensitivity score' that we derived from Pearson's correlation coefficient r and linear regression parameters. The highest sensitivity score was obtained by parallel capacitance at an alternating current frequency of 116 Hz in three-terminal configuration. Using a clamp, instead of a needle, as a stem electrode did not significantly affect the capacitance measurements. Finally, in handheld LCR meter equivalent conditions, capacitance had the highest sensitivity score and determination coefficient (r (2) = 0.52) at 10 kHz frequency. CONCLUSION: Our benchmarking of linear correlations between different electrical variables and root dry mass enables to determine more coherent practices for ensuring a sensitive and robust root dry mass estimation, including in handheld LCR meter conditions. This would enhance the value of electrical capacitance as a tool for screening crops in relation with root systems in breeding programs.

Spectral and thermal characterization of salophen type Schiff base and its implementation as solid contact electrode for quantitative monitoring of copper(II) ion.

Salophen templated Schiff base 2,3-bis(salicylaldimino)pyridine (H2IF) has been synthesized and fully characterized by a series of different spectroscopic methods and thermogravimetric analysis (TGA). It has been also further probed electrochemically and explored as a cation recognition ionophore in the form of a polymeric membrane as selective sensor for quantitative monitoring of Cu(2+). Dielectric properties of the membrane have been studied by electrochemical impedance spectroscopy (EIS). The potentiometric results have demonstrated that the sensor exhibits very good selectivity and sensitivity towards Cu(2+) over a wide variety of cations. The electrode has a linear response to Cu(2+) with a detection limit of 4.46×10(-8) and displays a Nernstian slope (29.14 mV/decade) between pH 3.0 and 6.0 with a fast response time less than 10s. The solid contact electrodes have been exploited over five mounts period with good reproducibility. The analytical availability of the proposed electrode has been evaluated by applying in the determination of Cu(2+) ions in water samples. The structural features and complexation of ionophore with Cu(2+) have been monitored by UV-Vis spectroscopy and spectral findings have been further supported by DFT and TD-DFT calculations.

Development of Novel Non-Contact Electrodes for Mobile Electrocardiogram Monitoring System.

Real-time monitoring of cardiac health is helpful for patients with cardiovascular disease. Many telemedicine systems based on ubiquitous computing and communication techniques have been proposed for monitoring the user's electrocardiogram (ECG) anywhere and anytime. Usually, wet electrodes are used in these telemedicine systems. However, wet electrodes require conduction gels and skin preparation that can be inconvenient and uncomfortable for users. In order to overcome this issue, a new non-contact electrode circuit was proposed and applied in developing a mobile electrocardiogram monitoring system. The proposed non-contact electrode can measure bio-potentials across thin clothing, allowing it to be embedded in a user's normal clothing to monitor ECG in daily life. We attempted to simplify the design of these non-contact electrodes to reduce power consumption while continuing to provide good signal quality. The electrical specifications and the performance of monitoring arrhythmia in clinical settings were also validated to investigate the reliability of the proposed design. Experimental results show that the proposed non-contact electrode provides good signal quality for measuring ECG across thin clothes.