Reusable Electrodes Research Articles

3D-printed electrochemical cells for multi-point aptamer-based drug measurements.

Electrochemical aptamer-based (E-AB) sensors achieve detection and quantitation of biomedically relevant targets such as small molecule drugs and protein biomarkers in biological samples. E-ABs are usually fabricated on commercially available macroelectrodes which, although functional for rapid sensor prototyping, can be costly and are not compatible with the microliter sample volumes typically available in biorepositories for clinical validation studies. Seeking to develop a multi-point sensing platform for sensor validation in sample volumes characteristic of clinical studies, we report a protocol for in-house assembly of 3D-printed E-ABs. We employed a commercially available 3D stereolithographic printer (FormLabs, $5k USD) for electrochemical cell fabrication and directly embedded electrodes within the 3D-printed cell structure. This approach offers a reproducible and reusable electrode fabrication process resulting in four independent and simultaneous measurements for statistically weighted results. We demonstrate compatibility with aptamer sequences binding antibiotics and antineoplastic agents. We also demonstrate a proof-of-concept validation of serum vancomycin measurements using clinical samples. Our results demonstrate that 3D-printing can be used in conjunction with E-ABs for accessible, rapid, and statistically meaningful validation of E-AB sensors in biological matrices.

Assessment of bioimpedance spectroscopy devices: a comparative study and error analysis of gold-plated copper electrodes

Objective. Bioimpedance spectroscopy (BIS) is a non-invasive diagnostic tool to derive fluid volume compartments from frequency dependent voltage drops in alternating currents by extrapolating to the extracellular resistance (R 0) and intracellular resistance (R i). Here we tested whether a novel BIS device with reusable and adhesive single-use electrodes produces results which are (in various body positions) equivalent to an established system employing only single-use adhesive electrodes. Approach. Two BIS devices (‘Cella’ and the ‘Body Composition Monitor’ [BCM]) were compared using four dedicated resistance testboxes and by measuring 40 healthy volunteers. In vivo comparisons included supine wrist-to-ankle (WA) reference measurements and wrist-to-wrist (WW) measurements with pre-gelled silver/silver-chloride (Ag/AgCl) electrodes and WW measurements with reusable gold-plated copper electrodes. Main results. Coefficient of variation were <1% for all testbox measurements with both BIS devices. Accuracy was within ±1% of true resistance variability, a threshold which was only exceeded by the Cella device for all resistances in a testbox designed with a low R 0/R i ratio. In vivo, WA-BIS differed significantly between BIS devices (p < 0.001). Reusable WW electrodes exhibited larger resistances than WW-BIS with Ag/AgCl electrodes (R 0: 738.36 and 628.69 Ω; R i: 1508.18 and 1390 Ω) and the relative error varied from 7.6% to 31.1% (R 0) and −15.6% to 37.3% (R i). Significance. Both BIS devices produced equivalent resistances measurements but different estimates of body composition both in silico and in WA setups in vivo, suggesting that the devices should not be used interchangeably. Employing WW reusable electrodes as opposed to WA and WW measurement setups with pre-gelled Ag/AgCl electrodes seems to be associated with measurement variations that are too large for safe clinical use. We recommend further investigations of measurement errors originating from electrode material and current path.

(Invited) Electrocatalytic Syntheses with Interfacial Control

Synthesis driven by renewable electricity offers a sustainable, scalable, decentralized, and energy-efficient route to furnish value-added products. As all electrocatalytic reactions occur at the phase boundary between conductive solids and liquid electrolytes, the discovery, design, and manipulation of selective electricity-driven reactivity demands new methods to probe and tune this interface and predict how interfacial structural changes influence reaction selectivity.The functionalization of aldehydes and ketones with organic halide electrophiles remains a privileged reaction class to construct C(sp3)‒C(sp3) bonds. Translation to molecular catalytic strategies remains challenging due to competitive side reactivity imposed by radical intermediates following sp3 organic halide activation. Our group has uncovered an alternative paradigm that deploys catalytic electrode surfaces to develop reductive fragment-based electrophile coupling reactions. Using in-situ spectroscopy and electrochemical analyses, we reveal the “black box” of the catalytic interface. The addition of Lewis acids pre-organizes the surface, enabling a carbon-centered radical (obtained via electrocatalytic activation) to efficiently add to the carbonyl. Our studies lay a foundation to develop sustainable synthetic methodologies by tuning the interfacial structure at catalytic, reusable electrodes at the molecular level.

Immobilization-Free Photoelectrochemical Aptasensor for Atrazine Based on Bifunctional Graphene Signal Amplification and a Controllable Sulfhydryl-Assembled BiOBr/Ag NP Microinterface.

Immobilization-free sensors (IFSs), with no requirement of fixing the recognition element to the electrode surface, have received increasing attention due to their unique advantages of reusable electrodes, not being limited by the load of the recognition element, and not being easily changed to the structure of the probe. In the present work, an effective visible light-driven immobilization-free photoelectric aptasensor for ultrasensitive detection of atrazine (ATZ) was proposed based on a reusable BiOBr/Ag NP substrate electrode with ultrafast charge transfer. Controllable thiols were used as conditioning agents for the photoelectric signal. The ingeniously designed bifunctional graphene can act as not only a molecular "bridge" for the ATZ aptamer through a strong π-π stacking effect, obtaining a graphene-aptamer complex, serving as a homogeneous recognition element, but also a switch for signal modulation for quantitative detection of target substances. Benefiting from the synergistic effect of the above-mentioned factors, the proposed sensor is capable of ultrasensitive and highly selective detection of ATZ in real water samples with a low detection limit of 1.2 pM and a wide linear range from 5.0 pM to 10.0 nM. Furthermore, it shows high stability, good selectivity, and strong anti-interference ability. Thus, this work has provided a fresh perspective for designing advanced immobilization-free photoelectric sensors and convenient detection of environmental pollutants.

Plastic antibodies integrated with graphene quantum dots for electrochemical sensing of bisphenol-A in real samples

Bisphenol-A (BPA) is a hazardous chemical used in plastic manufacturing units. BPA is recognized as an endocrine disruptor that can act as environmental estrogen and affect the activity of natural endogenous hormones. BPA is both genotoxic and cytotoxic; hence, developing a sensor for its recognition and quantification is essential. In this study, a molecularly imprinted polymer (MIP) based electrochemical sensor was developed for the analysis of Bisphenol-A (BPA). The fabrication of BPA/PEDOT/GQDs/AuNPs/GCE was carried out by electrodepositing the gold (Au) nanoparticles followed by electropolymerization employing 3,4-ethylenedioxythiophene (EDOT) and in-situ graphene quantum dots (GQDs). The characterization was performed using numerous techniques such as FESEM, XRD, UV–vis, TEM, FTIR, and electrochemical techniques. The linear range for the detection of Bisphenol-A was 1 nM to 50 µM with a low detection limit (LOD) of 0.19 nM and a limit of quantification (LOQ) of 0.64 nM. The proposed method delivered selective, sensitive, and reusable electrodes for the detection of BPA. The recovery was found to be 95–112% and the fabricated electrode was successfully utilized for the analysis of BPA in the real samples.

#4657 COMPARISON OF TWO BIOIMPEDANCE SPECTROSCOPY DEVICES: A PRACTICAL STEP FORWARD ON THE WAY TO DAILY BIOIMPEDANCE MEASUREMENTS FOR DIALYSIS PATIENTS

Abstract Background and Aims Bioimpedance spectroscopy (BIS) is a non-invasive diagnostic tool to assess volume status and body composition through the measurement of voltage drops in alternating currents and subsequent extrapolation of extracellular (R0), intracellular (Ri), and total body (RInf) resistances. Currently available devices mostly rely on disposable electrodes and require supine body position. Here we tested whether a new, more versatile BIS device with reusable electrodes matches an established system in various setups, aiming to enable daily BIS-measurements in the near future. Method Two BIS devices (“Cella” and the “Body Composition Monitor” [BCM]) were compared both with four resistance testboxes (circuit boards with resistors and capacitors simulating different body conditions) and in 40 healthy volunteers. In-vivo comparisons included supine hand-to-foot (HF) reference measurements with adhesive disposable electrodes and hand-to-hand (HH) measurements with adhesive disposable and prototype reusable electrode sets (Figure 1). Results Analyses of testboxes were reproducible in both devices (intra-device coefficients of variation &amp;lt;1%). Mean differences from testbox components were similar and small for R0 (2-3 Ohm) but not for Ri, where Cella was off by 101 Ohm compared to the BCM's 29 Ohm in a testbox designed with a deliberately low R0/Ri ratio. In-vivo, HF measurements with disposable electrodes differed significantly between both devices (p &amp;lt; 0.001). Prototype reusable HH electrodes exhibited a bias towards larger resistances than HF measurements (R0: 738.36 Ohm vs. 643.09 Ohm; Ri: 1508.18 Ohm vs. 1257.17 Ohm; RInf 500.03 vs. 423.81 Ohm, respectively) and the HH/HF ratio varied between 1.0-1.4 (R0 and RInf) and 0.9-1.6 (Ri). Conclusion While the Cella BIS device was shown to produce results with comparable consistency to the BCM in-vivo, the latter measured more accurately under testbox conditions. Accuracy of in-vivo measurements could not be determined for lack of gold-standard measurements. Implementation of HH reusable electrodes will require per-patient calibration against HF measurements due to the large inter-patient fluctuations in the HH/HF ratio. We recommend further longitudinal analyses of intra-patient HH/HF ratios to investigate long-term variabilities.

A novel strategy for fabrication, activation and cleaning of fully 3D printed flexible planar electrochemical platforms

AbstractIn recent years, 3D printing of carbon‐based conductive filaments has received growing attention for assembling electrodes to be used in a wide variety of electroanalytical devices and applications. Despite the large amount of work present in literature concerning the development of three‐dimensional (3D) conductive structures, its potential as dry deposition method for assembling two‐dimensional (2D) electrodes to be used in planar configuration is still largely unexplored. In fact, the possibility to rapidly change the geometry of the electrochemical circuits, associated with the reduction of waste and the absence of solvents, which are instead important components of ink and paste formulations, makes this strategy a valid green and efficient alternative to other deposition approaches such as screen‐printing technology. We report here a rapid and solvent‐free method for assembling fully 3D printed flexible planar electroanalytical platforms (3DEPs) to be used with microliters of liquid. At the same time, a novel protocol for the surface pre‐treatment of 3D printed electrodes based on ultrasonication in aqueous NaOH solution followed by electrochemical activation using the same medium, is presented. In addition, the same procedure has proved to be efficient for cleaning the electrode surface after electrochemical passivation, thus confirming the validity of both time‐efficient and environmentally‐friendly assembling and activation/cleaning procedures developed which allow efficient and reusable electrodes to be produced. Finally, 3DEPs were tested by a proof‐of‐concept quantification of a commonly used food dye (Brilliant Blue, E‐133) in commercial solutions used for homemade food coloring.

Highly Stable and Reusable 3D Graphene-Quinizarin Voltammetric pH Sensor

A simple pH sensor has been developed employing a 3D porous graphene framework blended with quinizarin. The performance of the fabricated sensor is tested via the square wave voltammetry technique by applying different buffer solutions and real samples. The peak potential of the designed electrode varies with the change in pH of solutions due to 2e−/2H+ transfer process of pH-dependent quinone/hydroquinone redox couple. For varying pH (1–13), the designed sensor has a sensitivity of 65.6 ± 0.4 mV/pH at 25 °C. Soil pH sensing is performed for different types of soil samples prepared using 1M KCl and 0.01M CaCl2 solutions with a potential shift of 63.5 ± 0.9 mV/pH and 57.9 ± 0.3 mV/pH, respectively. The 3D graphene-quinizarin pH sensing probe demonstrates negligible hysteresis (± 0.3 pH) and long-term stability (six months and more). In comparison to the commercial pH meter, the fabricated sensor shows a relative inaccuracy of less than 5%. Moreover, a single electrode could be used to detect the pH of multiple environments by mild rinsing with deionized water and is reusable for more than 500 cycles without significant potential drift. These low-cost and reusable pH-sensitive electrodes with linear Nernstian response are promising candidates for diverse pH-sensing applications.

Reusable Electronic Tongue Based on Transient Receptor Potential Vanilloid 1 Nanodisc-Conjugated Graphene Field-Effect Transistor for a Spiciness-Related Pain Evaluation.

The sense of spiciness is related to the stimulation of vanilloid compounds contained in the foods. Although, the spiciness is commonly considered as the part of taste, it is more classified to the sense of pain stimulated on a tongue, namely, pungency, which is described as a tingling or burning on the tongue. Herein, first, a reusable electronic tongue based on a transient receptor potential vanilloid 1 (TRPV1) nanodisc conjugated graphene field-effect transistor is fabricated and spiciness-related pain evaluation with reusable electrode is demonstrated. The pungent compound reactive receptor TRPV1 is synthesized in the form of nanodiscs to maintain stability and reusability. The newly developed platform shows highly selective and sensitive performance toward each spiciness related vanilloid compound repeatably: 1 aM capsaicin, 10 aM dihydrocapsaicin, 1 fM piperine, 10nM allicin, and 1 pM AITC. The binding mechanism is also examined by simulation. Furthermore, the elimination of the burning sensation on the tongue after eating spicy foods is not investigated. Based on the synthesis of micelles composed of casein protein (which is contained in skim milk) that remove pungent compounds bound to TRPV1 nanodisc, the deactivation of TRPV1 is investigated, and the electrode is reusable that mimics electronic tongue.

Generalizable Deep Learning-based Sleep Staging Approach for Ambulatory Textile Electrode Headband Recordings.

Reliable, automated, and user-friendly solutions for the identification of sleep stages in home environment are needed in various clinical and scientific research settings. Previously we have shown that signals recorded with an easily applicable textile electrode headband (FocusBand, T 2 Green Pty Ltd) contain characteristics similar to the standard electrooculography (EOG, E1-M2). We hypothesize that the electroencephalographic (EEG) signals recorded using the textile electrode headband are similar enough with standard EOG in order to develop an automatic neural network-based sleep staging method that generalizes from diagnostic polysomnographic (PSG) data to ambulatory sleep recordings of textile electrode-based forehead EEG. Standard EOG signals together with manually annotated sleep stages from clinical PSG dataset (n = 876) were used to train, validate, and test a fully convolutional neural network (CNN). Furthermore, ambulatory sleep recordings including a standard set of gel-based electrodes and the textile electrode headband were conducted for 10 healthy volunteers at their homes to test the generalizability of the model. In the test set (n = 88) of the clinical dataset, the model's accuracy for 5-stage sleep stage classification was 80% (κ = 0.73) using only the single-channel EOG. The model generalized well for the headband-data, reaching 82% (κ = 0.75) overall sleep staging accuracy. In comparison, accuracy of the model was 87% (κ = 0.82) in home recordings using the standard EOG. In conclusion, the CNN model shows potential on automatic sleep staging of healthy individuals using a reusable electrode headband in a home environment.

EEG sensor system development consisting of solid polyvinyl alcohol–glycerol–NaCl contact gel and 3D-printed, silver-coated polylactic acid electrode for potential brain–computer interface use

The paper describes the development of a reusable electrode system for non-invasive brain–computer interface application with signal quality comparable to that of conventional wet Ag/AgCl electrodes. The innovative electrode system consists of a polyvinyl alcohol–glycerol–NaCl contact hydrogel and a 3D-printed, silver-coated polylactic acid electrode body. Advantageous features of the proposed system are the comfortable use, reusability, long shelf life, and alterable geometry. The electrical properties of freshly prepared and aged contact gels, as well as different gel/silver interfaces, were separately characterized, showing much lower impedance values than those measured at the electrode–skin interface with the complete electrode system. Acceptability limits relevant to electroencephalographic measurements, such as signal-to-noise ratio during steady-state visually evoked potential measurements and band ratio values during alpha wave detection, have proven the applicability of the system.

Carbon monoliths with programmable valence bands as de novo anodes for additive-free coupling of alcohols into acetals

Designing functional and reusable electrode materials to replace homogeneous versions of scarifying additives or mediators in electrochemical organic synthesis is of great importance for both the fundamental academics and practical production of various useful compounds. Herein, we rediscover the function of nitrogen-doped carbon monoliths (NxC) as de novo anode materials to trigger a new reaction path for the synthesis of acetals from the direct coupling of alcohols without the assistance of any mediator, oxidant, acid, or organic ligand. The lowered valence bands of carbon monoliths induced by doping nitrogen are of key importance for polarizing and activating the pre-adsorbed O–H groups of benzyl alcohol molecules to boost the high Faradaic efficiency (71% at 1.8 V versus Ag/AgCl) and reusability of NxC anodes, meeting the requirements of green chemistry.

Electrical Characterization of Cellulose-Based Membranes towards Pathogen Detection in Water.

Paper substrates are promising for development of cost-effective and efficient point-of-care biosensors, essential for public healthcare and environmental diagnostics in emergency situations. Most paper-based biosensors rely on the natural capillarity of paper to perform qualitative or semi-quantitative colorimetric detections. To achieve quantification and better sensitivity, technologies combining paper-based substrates and electrical detection are being developed. In this work, we demonstrate the potential of electrical measurements by means of a simple, parallel-plate electrode setup towards the detection of whole-cell bacteria captured in nitrocellulose (NC) membranes. Unlike current electrical sensors, which are mostly integrated, this plug and play system has reusable electrodes and enables simple and fast bacterial detection through impedance measurements. The characterized NC membrane was subjected to (i) a biofunctionalization, (ii) different saline solutions modelling real water samples, and (iii) bacterial suspensions of different concentrations. Bacterial detection was achieved in low conductivity buffers through both resistive and capacitive changes in the sensed medium. To capture Bacillus thuringiensis, the model microorganism used in this work, the endolysin cell-wall binding domain (CBD) of Deep-Blue, a bacteriophage targeting this bacterium, was integrated into the membranes as a recognition bio-interface. This experimental proof-of-concept illustrates the electrical detection of 107 colony-forming units (CFU) mL−1 bacteria in low-salinity buffers within 5 min, using a very simple setup. This offers perspectives for affordable pathogen sensors that can easily be reconfigured for different bacteria. Water quality testing is a particularly interesting application since it requires frequent testing, especially in emergency situations.

Electrochemical Removal of Copper Ion Using Coconut Shell Activated Carbon

In this work, coconut shell activated carbon (CSAC) electrode was evaluated to remove copper ion via electrochemical processes. CSAC electrode and graphite were applied as the cathode and the anode, respectively. The reusability of the electrode, the effects of initial pH, applied voltage and initial concentration were studied. The electrochemical process was carried out for 3 h of treatment time, and the electrodes (anode and cathode) were separated by 1 cm. The results revealed that CSAC is proven as a reusable electrode to remove copper ion, up to 99% of removal efficiency from an initial concentration of 50 ppm after it had been used three times. From the observation, the removal efficiency was optimum at an initial pH of 4.33 (without any initial pH adjustment). The applied voltage at 8 V showed a higher removal efficiency of copper ion compared to at 5 V.

Supporting front crawl swimming in paraplegics using electrical stimulation: a feasibility study

BackgroundParticipation in physical and therapeutic activities is usually severely restricted after a spinal cord injury (SCI). Reasons for this are the associated loss of voluntary motor function, inefficient temperature regulation of the affected extremities, and early muscle fatigue. Hydrotherapy or swim training offer an inherent weight relief, reduce spasticity and improve coordination, muscle strength and fitness.MethodsWe present a new hybrid exercise modality that combines functional electrical stimulation (FES) of the knee extensors and transcutaneous spinal cord stimulation (tSCS) with paraplegic front crawl swimming. tSCS is used to stimulate the afferent fibers of the L2–S2 posterior roots for spasticity reduction. By activating the tSCS, the trunk musculature is recruited at a motor level. This shall improve trunk stability and straighten the upper body. Within this feasibility study, two complete SCI subjects (both ASIA scale A, lesion level Th5/6), who have been proficient front crawl swimmers, conducted a 10-week swim training with stimulation support. In an additional assessment swim session nine months after the training, the knee extension, hip extension, and trunk roll angles where measured using waterproof inertial measurement units (IMUs) and compared for different swimming conditions (no stimulation, tSCS, FES, FES plus tSCS).ResultsFor both subjects, a training effect over the 10-week swim training was observed in terms of measured lap times (16 m pool) for all swimming conditions. Swimming supported by FES reduced lap times by 15.4% and 8.7% on average for Subject A and Subject B, respectively. Adding tSCS support yielded even greater mean decreases of 19.3% and 20.9% for Subjects A and B, respectively. Additionally, both subjects individually reported that swimming with tSCS for 30–45 minutes eliminated spasticity in the lower extremities for up to 4 hours beyond the duration of the session. Comparing the median as well as the interquartile range of all different settings, the IMU-based motion analysis revealed that FES as well as FES+tSCS improve knee extension in both subjects, while hip extension was only increased in one subject. Trunk roll angles were similar for all swimming conditions. tSCS had no influence on the knee and hip joint angles. Both subjects reported that stimulation-assisted swimming is comfortable, enjoyable, and they would like to use such a device for recreational training and rehabilitation in the future.ConclusionsStimulation-assisted swimming seems to be a promising new form of hybrid exercise for SCI people. It is safe to use with reusable silicone electrodes and can be performed independently by experienced paraplegic swimmers except for transfer to water. The study results indicate that swimming speed can be increased by the proposed methods and spasticity can be reduced by prolonged swim sessions with tSCS and FES. The combination of stimulation with hydrotherapy might be a promising therapy for neurologic rehabilitation in incomplete SCI, stroke or multiples sclerosis patients. Therefore, further studies shall incorporate other neurologic disorders and investigate the potential benefits of FES and tSCS therapy in the water for gait and balance.

SYNTHESIS, PHOTO- AND ELECTROCATALYTIC PROPERTIES OF NANOSTRUCTURED Ce–TiO2 FILMS

Electrocatalytic films based on nanodispersed titanium dioxide modified by Ce(III) were synthesized by sol-gel method and characterized by X-ray diffraction and ultraviolet-visible photocurrent spectra. The average size of nanoparticles was no more thаn 11 nm. The XRD results indicated that TiO2 and Ce–TiO2 electrodes with Ce concentrations up to 5 % calcined at 500°C consisted of anatase as the unique phase. The photocurrent spectra of the Ce–TiO2 electrodes (0 ≤ Ce concentration ≤ 2% mol.) showed a stronger current in the UV range and a shift in the flat-band potential (Еfb) towards more negative values than that of TiO2 electrodes. Electrocatalytic properties of TiO2 and Ce–TiO2 electrodes were investigated in the process of oxygen electroreduction. It has been found by I–E curves measurements that the potential of oxygen reduction changes with the film composition. Modifying of TiO2 films by Ce(III) improves catalytic activity of Ce–TiO2 electrodes ( Ce concentration up to 2% mol.) in the reaction of oxygen electroreduction, that appears in decreasing of oxygen reduction potential EO2 and increasing of dynamic range of O2 electroreduction potentials. The high electrocatalytic activity of Ce–TiO2 electrodes in the oxygen reduction process may be due to the formation of catalytically active centers which activity may decrease in the presence of an amorphous phase. The correlation between photo- and electrocatalytic properties and structural changes occurring in Ce–TiO2 films on increasing the cerium content is observed. The electrodes investigated were distinguished by a high sensitivity to dissolved oxygen ((4-5)∙10-6 g·l-1) and high reproducibility of characteristics in long-time cycling. These electrodes promise much as reusable electrode materials in electrochemical sensors for the determination of oxygen in liquids.

The Dependence of Electrode Impedance on the Number of Performed EEG Examinations.

In clinical practice, it is recommended to employ reusable electrodes for the registration of brain waves. Before registering EEG signals, the EEG technician checks the condition of all the electrodes, i.e., the occurrence of mechanical damage and the color of the electrode coating. It should be noticed that there is still no information on the permissible number of EEG examinations performed with one set of electrodes. After placement of the electrodes on the patient’s head, the scalp–electrode impedance is measured with the use of EEG equipment. When the scalp–electrode impedance achieves a value above 5 kΩ, it is necessary to replace the given electrode or to re-execute skin abrasion. The Electrochemical Impedance Spectroscopy (EIS) method was used in order to estimate the permissible number of EEG examinations performed with one set of electrodes. Ten new reusable electrodes were tested. Then, the tests were repeated after subsequent uses of those electrodes. The conducted tests led us to the conclusion that the permissible number of examinations performed with one set of electrodes is up to twenty except for the gold electrodes for which it is up to ten. Furthermore, the use of the EIS method revealed variability of impedance in the case of new electrodes.

Reusable Electroencephalography Electrodes: Variability in Cleaning and Reprocessing Practices

ABSTRACTOf 124 reusable electroencephalography cup electrodes/lead wires from four epilepsy monitoring units, 25% had bacterial growth. Institutional cleaning practices of electroencephalography cup electrode lead wires may contribute to positive culture prevalence. In this study, personnel who supervised cleaning of electroencephalography cup electrodes/lead wires completed an investigator-developed survey. Generalized mixed-effect models compared sites, including storage area within site as a random effect, to adjust for correlation between wires stored in the same location. Odds ratios and 95% confidence intervals were calculated. Of nine characteristics (transportation time, wait time pre-cleaning, storage pre-cleaning [covered or not covered], disinfection time, cleaning time, bundled cleaning [always, frequently, or occasionally], drying practice [towel or air], drying time, and storage post-cleaning [covered or not covered]), when drying time was less than or equal to 5 minutes, there was a 71% decrease in the odds of positive bacterial cultures (odds ratio [95% confidence interval]: 0.29 [0.09, 0.97], P = 0.045). Further, when cleaning time was not rushed (greater than 1 hour after removal from patient care) and multiple sets of electroencephalography cup electrodes were cleaned at once, there was a trend toward fewer positive bacterial cultures (odds ratios [95% confidence intervals] for both factors: 0.16 [0.02, 1.40], P = 0.092). Microorganisms were found on cleaned electroencephalography cup electrode lead wires in each of four hospital-based epilepsy monitoring units, despite cleaning practices. When cleaning and reprocessing practice characteristics were assessed, site variation was high, and some cleaning practices were associated with higher rates of positive bacterial cultures.

Study on Reusable Electrodes for Personal Electrocardiography

Electrodes are an important part of electrocardiography (ECG); disposable electrodes have been extensively used. However, personal ECG monitoring devices for Internet of Things applications require reusable electrodes. As there have been no systematic studies on the characteristics of reusable electrodes to date, we conducted this study to assess the performance and feasibility of electrodes with different materials. We built reusable electrodes using twelve different metallic materials, including commonly used copper, silver, zinc, plating materials, chemically inert titanium, stainless steel, and aluminum. Each electrode was fabricated to a size of 5 × 10 mm. Their characteristics such as offset, baseline drift, stabilization time, and chemical inertness were compared. A personal ECG monitoring system was used to test the manufactured electrodes. The performances of the Ag, Cu, and Zn electrodes were better than the performances of other electrodes. However, these materials may not be used owing to the chemical changes that occur when the electrodes are in contact with the skin, such as discoloration and corrosion, which deteriorate their electrical characteristics. Titanium, stainless steel, and aluminum are chemically stable. The titanium electrode showed the best performance among the three, and it is our recommendation as a material for manufacturing reusable electrodes.

Dielectrophoresis-based multi-step nanowire assembly on a flexible superstrate

Nanowire assembly based on dielectrophoresis (DEP) could be a useful and efficient tool for fabricating nanowire-based devices. Although there have been extensive reports on the DEP nanowire assembly, the new approaches that make DEP more facile and affordable are still desirable. Herein, we present an approach using the reusable electrodes to assemble silver nanowires onto a removable, independent polyethylene terephthalate (PET) film. The PET film is placed on the reusable electrodes, and a sinusoidal AC voltage is applied to the electrodes to induce DEP force for nanowire assembly upon the flexible film. We explore the influences of voltage, frequency and film thickness on nanowire assembly and further realize the assembly of silver nanowire arrays. In addition, the induced electric field is rotated in two consecutive steps to assemble the rectangular mesh-like nanowire networks. This reusable and facile approach for DEP nanowire assembly could provide a low-cost, precise, rapid and convenient tool for applications in the fields of flexible electronics.