Electric Potential In Response Research Articles

Response of a novel all-solid-state sodium-based-electrolyte battery to quasi-static and dynamic stimuli

In response to growing environmental and economic concerns, developing new technologies prioritising safety, sustainability, and reliability has become imperative. In the energy sector, batteries play an increasingly significant role in applications such as powering electronic devices and vehicles. In this context, lithium-ion batteries have raised environmental concerns, driving the exploration of alternative technologies. Sodium-based batteries have emerged as an attractive option due to their environmental and economic advantages, as well as their potential for multi-functional applications. This study investigates a novel battery developed by a research team at the University of Porto, with a specific focus on its strain-sensing capabilities for potential applications in damage detection of structures. The battery under investigation is a novel all-solid-state design, comprised of a sodium-ion ferroelectric electrolyte and zinc and copper as the negative and positive electrodes, respectively. A series of quasi-static and dynamic tests are conducted to qualitatively assess the piezoelectric behaviour of the battery. The consistent findings show that the battery generates a difference in the electric potential in response to mechanical stimuli, thus confirming its piezoelectric nature. Furthermore, the results demonstrate the battery can accurately detect the operating frequencies of a shaker, despite encountering inherent electromagnetic interference noise from the electrical grid during testing. These promising outcomes highlight the substantial potential of this emerging technology for a wide range of applications, including but not limited to structural health monitoring systems. Given its novelty, this technology presents multi-functional capabilities for diverse practical future applications, such as energy harvesting that leads to self-powered structural health monitoring systems.

Machine Learning Classification of Event-Related Brain Potentials during a Visual Go/NoGo Task.

Machine learning (ML) methods are increasingly being applied to analyze biological signals. For example, ML methods have been successfully applied to the human electroencephalogram (EEG) to classify neural signals as pathological or non-pathological and to predict working memory performance in healthy and psychiatric patients. ML approaches can quickly process large volumes of data to reveal patterns that may be missed by humans. This study investigated the accuracy of ML methods at classifying the brain's electrical activity to cognitive events, i.e., event-related brain potentials (ERPs). ERPs are extracted from the ongoing EEG and represent electrical potentials in response to specific events. ERPs were evoked during a visual Go/NoGo task. The Go/NoGo task requires a button press on Go trials and response withholding on NoGo trials. NoGo trials elicit neural activity associated with inhibitory control processes. We compared the accuracy of six ML algorithms at classifying the ERPs associated with each trial type. The raw electrical signals were fed to all ML algorithms to build predictive models. The same raw data were then truncated in length and fitted to multiple dynamic state space models of order nx using a continuous-time subspace-based system identification algorithm. The 4nx numerator and denominator parameters of the transfer function of the state space model were then used as substitutes for the data. Dimensionality reduction simplifies classification, reduces noise, and may ultimately improve the predictive power of ML models. Our findings revealed that all ML methods correctly classified the electrical signal associated with each trial type with a high degree of accuracy, and accuracy remained high after parameterization was applied. We discuss the models and the usefulness of the parameterization.

Application of direct electrometry in studies of microbial rhodopsins reconstituted in proteoliposomes.

Microbial rhodopsins are the family of retinal-containing proteins that perform primarily the light-driven transmembrane ion transport and sensory functions. They are widely distributed in nature and can be used for optogenetic control of the cellular activities by light. Functioning of microbial rhodopsins results in generation of the transmembrane electric potential in response to a flash that can be measured by direct time-resolved electrometry. This method was developed by L. Drachev and his colleagues at the Belozersky Institute and successfully applied in the functional studies of microbial rhodopsins. First measurements were performed using bacteriorhodopsin from Halobacterium salinarum-the prototype member of the microbial retinal protein family. Later, direct electrometric studies were conducted with proteorhodopsin from Exiguobacterium sibiricum (ESR), the sodium pump from Dokdonia, and other proteins. They allowed detailed characterization of the charge transfer steps during the photocycle of microbial rhodopsins and provided new insights for profound understanding of their mechanism of action.

In Vivo Basilar Membrane Time Delays in Humans.

To date, objective measurements and psychophysical experiments have been used to measure frequency dependent basilar membrane (BM) delays in humans; however, in vivo measurements have not been made. This study aimed to measure BM delays by performing intracochlear electrocochleography in cochlear implant recipients. Sixteen subjects with various degrees of hearing abilities were selected. Postoperative Computer Tomography was performed to determine electrode locations. Electrical potentials in response to acoustic tone pips at 0.25, 0.5, 1, 2, and 4 kHz and clicks were recorded with electrodes at the frequency specific region. The electrode array was inserted up to the characteristic cochlear frequency region of 250 Hz for 6 subjects. Furthermore, the array was inserted in the region of 500 Hz for 15 subjects, and 1, 2, and 4 kHz were reached in all subjects. Intracochlear electrocochleography for each frequency-specific tone pip and clicks showed detectable responses in all subjects. The latencies differed among the cochlear location and the cochlear microphonic (CM) onset latency increased with decreasing frequency and were consistent with click derived band technique. Accordingly, BM delays in humans could be derived. The BM delays increased systematically along the cochlea from basal to apical end and were in accordance with Ruggero and Temchin, 2007.

Coping with electrode polarization for development of DC-Driven electrical impedance tomography

An electrical impedance tomography (EIT) system design is proposed for imaging of phase distribution in gas-water two-phase flow from boundary measurement of electrical potentials in response to direct current (DC) injection. DC injection simplifies substantially the system design, but introduces problems due to polarization of injection electrodes. Electrode polarization means charge accumulation on the electrode-water interface causing a drift in the interfacial potential difference. The polarization problems are coped with by using dedicated electrodes for injection and potential measurement, and using a current source unaffected by the polarization of current-carrying electrodes (CCEs). Furthermore, the polarization of CCEs is controlled, to lessen the possible influence on the sensing electrodes (SEs), by using a short (milliseconds in width) pulse for injection with a charge balanced injection strategy. The impact of electrode polarization and the effectiveness of countermeasures introduced in the present design are discussed through comparisons of measured boundary potentials and of images reconstructed for a simple object simulating large bubbles in water.

Vision evaluation by functional observational battery, operant behavior test, and light/dark box test in retinal dystrophic RCS rats versus normal rats

BackgroundVision plays a key role in some behavior tests for rats. Okayama University-type retinal prosthesis (OUReP) is a photoelectric dye-coupled polyethylene film which generates electric potential in response to light and stimulates nearby neurons. This study aims to assess vision in retinal dystrophic (RCS) rats, in comparison with normal rats, by selected behavior tests. We also examined whether the tests could detect vision changes in RCS rats with dye-coupled film implantation. MethodsData sets were 5 normal rats, 4 untreated RCS rats, 7 RCS rats with dye-coupled films implanted at the age of 7 weeks after excluding unsuccessful implantation at autopsy. Behavior tests chosen were landing foot splay and visual forelimb-placing response in the menu of functional observational battery, operant-conditioning lever-press response and light/dark box test. ResultsNormal visual placing response was significantly less frequent in untreated RCS rats at the age of 9 and 11 weeks, compared with normal rats (P = 0.0027, chi-square test) while normal response was significantly more frequent at the age of 9 weeks in RCS rats with dye-coupled film implantation, compared with untreated RCS rats (P = 0.0221). In operant-conditioning lever-press test, the correct response rate was significantly lower in untreated RCS rats than in normal rats at the age of 9 weeks (P < 0.05, Tukey-Kramer test) while the rate was not significantly different between normal rats and RCS rats with dye-coupled film implantation. In light/dark box test, the time to enter dark box was significantly shorter in normal rats, compared with untreated RCS rats or RCS rats with dye-coupled film implantation (P < 0.05, Tukey-Kramer test). ConclusionsBehavior tests of functional observational battery, operant-conditioning lever-press response and light/dark box test discriminated vision between normal rats and RCS rats. The visual placing response and operant-conditioning lever-press test might have sensitivity to detect vision recovery in RCS rats with OUReP implantation.

Visual Evoked Potential Recovery by Subretinal Implantation of Photoelectric Dye-Coupled Thin Film Retinal Prosthesis in Monkey Eyes With Macular Degeneration.

Retinal prosthesis or artificial retina is a promising modality of treatment for outer retinal degeneration, caused by primary and secondary loss of photoreceptor cells, in hereditary retinal dystrophy and age‐related macular degeneration, respectively. Okayama University‐type retinal prosthesis (OUReP) is a photoelectric dye‐coupled polyethylene film which generates electric potential in response to light and stimulates nearby neurons. The dye‐coupled films were implanted by vitreous surgery in the subretinal space of monkey eyes with macular degeneration which had been induced by cobalt chloride injection from the scleral side. A pilot 1‐month observation study involved 6 monkeys and a pivotal 6‐month observation study involved 8 monkeys. Of 8 monkeys in 6‐month group, 3 monkeys underwent dye‐coupled film removal at 5 months and were observed further for 1 month. The amplitude of visual evoked potential which had been reduced by macular degeneration did recover at 1 month after film implantation and maintained the level at 6 months. Optical coherence tomography showed no retinal detachment, and full‐field electroretinograms maintained a‐wave and b‐wave amplitudes, indicative of no retinal toxicity. Pathological examinations after 6‐month implantation showed structural integrity of the inner retinal layer in close apposition to dye‐coupled films. The implanted films which were removed by vitrectomy 5 months later showed light‐evoked surface electric potentials by scanning Kelvin probe measurement. The photoelectric dye‐coupled film (OUReP), which serves as a light‐receiver and a displacement current generator in the subretinal space of the eye, has a potential for recovering vision in diseases with photoreceptor cell loss, such as retinitis pigmentosa and age‐related macular degeneration.

Visual evoked potential in rabbits' eyes with subretinal implantation by vitrectomy of Okayama University-type retinal prosthesis (OURePTM).

Okayama University-type retinal prosthesis (OURePTM) is a photoelectric dye-coupled polyethylene film which generates electric potential in response to light and stimulates nearby neurons. This study aims to test surgical feasibility for subretinal film implantation and to examine functional durability of films in subretinal space. Dye-coupled films were implanted subretinally by vitrectomy in the right eye of normal white rabbits: 8 rabbits for 1 month and 8 rabbits for 6 months. The implanted films were removed by vitrectomy in 4 of these 8 rabbits in 1-month or 6-month implantation group. The films were also implanted in 4 rhodopsin-transgenic retinal dystrophic rabbits. Visual evoked potential was measured before film implantation as well as 1 or 6 months after film implantation, or 1 month after film removal. The films were successfully implanted in subretinal space of retinal detachment induced by subretinal fluid injection with a 38G polyimide tip. The retina was reattached by fluid-air exchange in vitreous cavity, retinal laser coagulation, and silicone oil injection. The ratios of P2 amplitudes of visual evoked potential in the implanted right eye over control left eye did not show significant changes between pre-implantation and post-implantation or post-removal (paired t-test). In Kelvin probe measurements, 4 pieces each of removed films which were implanted for 1 or 6 months showed proportional increase of surface electric potential in response to increasing light intensity. The film implantation was safe and implanted films were capable of responding to light.

Electrophysiological Evidence of the Basilar-Membrane Travelling Wave and Frequency Place Coding of Sound in Cochlear Implant Recipients

Aim: To obtain direct evidence for the cochlear travelling wave in humans by performing electrocochleography from within the cochlea in subjects implanted with an auditory prosthesis. Background: Sound induces a travelling wave that propagates along the basilar membrane, exhibiting cochleotopic tuning with a frequency-dependent phase delay. To date, evoked potentials and psychophysical experiments have supported the presence of the travelling wave in humans, but direct measurements have not been made. Methods: Electrical potentials in response to rarefaction and condensation acoustic tone bursts were recorded from multiple sites along the human cochlea, directly from a cochlear implant electrode during, and immediately after, its insertion. These recordings were made from individuals with residual hearing. Results: Electrocochleography was recorded from 11 intracochlear electrodes in 7 ears from 6 subjects, with detectable responses on all electrodes in 5 ears. Cochleotopic tuning and frequency-dependent phase delay of the cochlear microphonic were demonstrated. The response latencies were slightly shorter than those anticipated which we attribute to the subjects' hearing loss. Conclusions: Direct evidence for the travelling wave was observed. Electrocochleography from cochlear implant electrodes provides site-specific information on hair cell and neural function of the cochlea with potential diagnostic value.

Subretinal implantation of Okayama University-type retinal prosthesis (OURePTM) in canine eyes by vitrectomy.

Okayama University-type retinal prosthesis (OURePTM) is a photoelectric dye-coupled polyethylene film which generates electric potential in response to light and stimulates nearby neurons. This study aims to test surgical feasibility of subretinal implantation and functional durability of dye-coupled films in the subretinal space. The dye-coupled films were implanted subretinally by 25-gauge vitrectomy in the right eye of 11 normal beagle dogs: 2 dogs served for film removal after 5-month film implantation, 3 dogs for film removal after 3-month film implantation, 3 dogs for 3-month film implantation and pathological examination, and 3 dogs for sham surgery. The surface electric potential of the removed dye-coupled films in response to light was measured by the Kelvin Probe system. At surgery, rolled-up dye-coupled films in 5 × 5 mm square size could be inserted into subretinal space of retinal detachment induced by fluid injection with a 38-gauge polyimide tip. Retinal attachment was maintained by silicone oil injection in vitreous cavity. At autopsy, the retina in all dogs maintained the ganglion cell layer, inner and outer nuclear layers while it lost the outer segments in some part. All 5 sheets of removed dye-coupled films maintained the dye color. One sheet of the 5-month implanted film showed proportional increase of surface potential in response to increasing light intensity. Subretinal implantation of OURePTM by vitrectomy was technically feasible in canine eyes, and OURePTM maintained the function of generating light-evoked surface potential after 5 months in subretinal implantation.

Performance of photovoltaic arrays in-vivo and characteristics of prosthetic vision in animals with retinal degeneration

Loss of photoreceptors during retinal degeneration leads to blindness, but information can be reintroduced into the visual system using electrical stimulation of the remaining retinal neurons. Subretinal photovoltaic arrays convert pulsed illumination into pulsed electric current to stimulate the inner retinal neurons. Since required irradiance exceeds the natural luminance levels, an invisible near-infrared (915nm) light is used to avoid photophobic effects. We characterized the thresholds and dynamic range of cortical responses to prosthetic stimulation with arrays of various pixel sizes and with different number of photodiodes. Stimulation thresholds for devices with 140μm pixels were approximately half those of 70μm pixels, and with both pixel sizes, thresholds were lower with 2 diodes than with 3 diodes per pixel. In all cases these thresholds were more than two orders of magnitude below the ocular safety limit. At high stimulation frequencies (>20Hz), the cortical response exhibited flicker fusion. Over one order of magnitude of dynamic range could be achieved by varying either pulse duration or irradiance. However, contrast sensitivity was very limited. Cortical responses could be detected even with only a few illuminated pixels. Finally, we demonstrate that recording of the corneal electric potential in response to patterned illumination of the subretinal arrays allows monitoring the current produced by each pixel, and thereby assessing the changes in the implant performance over time.

Piezoelectric materials mimic the function of the cochlear sensory epithelium

Cochlear hair cells convert sound vibration into electrical potential, and loss of these cells diminishes auditory function. In response to mechanical stimuli, piezoelectric materials generate electricity, suggesting that they could be used in place of hair cells to create an artificial cochlear epithelium. Here, we report that a piezoelectric membrane generated electrical potentials in response to sound stimuli that were able to induce auditory brainstem responses in deafened guinea pigs, indicating its capacity to mimic basilar membrane function. In addition, sound stimuli were transmitted through the external auditory canal to a piezoelectric membrane implanted in the cochlea, inducing it to vibrate. The application of sound to the middle ear ossicle induced voltage output from the implanted piezoelectric membrane. These findings establish the fundamental principles for the development of hearing devices using piezoelectric materials, although there are many problems to be overcome before practical application.

Experimental investigation of a post-buckled piezoelectric beam with an attached central mass used to harvest energy

Recent advances in wireless electronics have outpaced concurrent advances in battery technology, and this has led to the emergence of vibrational energy harvesting as an alternative source of energy for low-power wireless devices. In particular, piezoelectric materials have been widely studied as an energy conversion mechanism due to their ability to generate electric potential in response to applied mechanical strain. This paper investigates the response of a buckled piezoelectric beam to harmonic base excitation. Forced buckled structures may exhibit snap-through behaviour, in which the structure rapidly deforms from one stable configuration to another. Of particular interest to this study is the effect of an attached mass on persistent snap-through behaviour, which has clear applications to energy harvesting due to its relatively large amplitude motion. It is shown experimentally that the addition of a small mass to the centre of the beam significantly broadens the frequency range over which snap-through is observed, which leads to increased power output over those frequencies. Additionally, it is shown that adding a centre mass can lower the threshold forcing amplitude above which persistent snap-through can occur. Finally, it is shown that for a particular forcing condition, there exists a nearly linear relationship between the applied mass and the power output by the snap-through response. A theoretical model was developed to describe the system’s behaviour, which agreed with experimental findings that an attached mass leads to broadened frequency response and a lower threshold for large amplitude response.

Application of the network simulation method to study the electrical response of ion-exchange membrane systems to pulsed electric fields

The transient electrical response of an ion-exchange membrane system to square shaped electric perturbations not only when the electric potential is the externally controlled variable but also when an electric current is imposed through the system, has been simulated using the network simulation method. The system under study is constituted by a cation-exchange membrane in which the fixed-charge is homogeneously distributed in space and two diffusion boundary layers on both sides of the membrane, the electric double layers at the interfaces being included. The time evolution of the counterion flux exiting from the system in response to a pulsed electric potential has been analyzed in order to establish the conditions in which the use of transient techniques in ion-exchange membranes can lead to intensification of the efficiency of electrodialysis. Also, the time evolution of the system electric potential in response to a pulsed electric current is analyzed and discussed. The counterion quantity exiting from the system and the energy consumption in pulse mode are evaluated and compared to those obtained from stationary electrodialysis.

Change in electric characteristics of membranes in response to taste stimuli with increasing amount of lipids in membrane matrix of PVC and plasticizer

Changes in membrane electric potential in response to taste substances were studied for membranes containing differing amounts of negatively charged lipids in the membrane matrix of polyvinyl chloride and plasticizer. Responses to quinine showing bitterness decreased systematically with increasing the quantity of charged lipids contained in the membrane, whereas the response did not depend on differences in the hydrocarbon chains of lipids. The mechanism is discussed qualitatively in terms of hydrophobicity and hydrophilicity of the membranes.

Light-induced membrane potential changes of epidermal and mesophyll cells in growing leaves of Pisum sativum

Light transiently depolarizes the membrane of growing leaf cells. The ionic basis for changes in cell membrane electrical potentials in response to light has been determined separately for growing epidermal and mesophyll cells of the argenteum mutant of pea (Pisum sativum L.). In mesophyll cells light induces a large, transient depolarization that depends on the external Cl− concentration, is unaffected by changes in the external Ca2+ or K+ concentration, is stimulated by K+-channel blockers tetraethylammonium (TEA+) and Ba2+, and is inhibited by 3-(3′-4′-dichlorophenyl)-1,1-dimethylurea (DCMU). In isolated epidermal tissue, light induces a small, transient depolarization followed by a hyperpolarization of the membrane potential. The depolarization is enhanced by increasing the external Ca2+ concentration and by addition of Ba2+, and is not sensitive to DCMU. Epidermal cells in contact with mesophyll display a depolarization resembling the response of the underlying mesophyll cells. The light-induced depolarization in mesophyll cells seems to be mediated by an increased efflux of Cl− while the membrane-potential changes in epidermal strips reflect changes in the fluxes of Ca2+ and in the activity of the proton-pumping ATPase.

Nasopharyngeal recordings separate retinal from optic nerve potentials.

Electrical potentials in response to single flashes and to pattern-reversal stimuli presented in Maxwellian view were recorded from several intranasal locations by withdrawing a nasopharyngeal electrode from the epipharynx through the nose in steps of 1 cm. From the anterior parts of the nose a waveform could be obtained resembling the corneal electroretinogram. In the epipharynx an ERG was recorded which was inverted in polarity. This reversal in polarity was explained by assuming an electrical dipole of the retina oriented parallel to the electrode path. When the electrode was below and behind the posterior pole of the eye ball a high-frequency activity of increased amplitude was observed the origin of which could not be explained by the retinal dipole. It is suggested that these increased oscillations originate from the optic nerve. Their behavior is explained by a hypothetical electrical dipole of the optic nerve oriented vertical to the electrode path.

On Hearing by Electrical Stimulation

The well-known fact that the ear generates an electric potential in response to stimulation by a sound wave has its counterpart in the fact that, when an alternating current is passed through the head, an auditory sensation results. The observer hears a tone whose pitch is determined by the frequency of the alternating current. Measurements were made of the power needed to elicit a sensation using currents of various frequencies. The power, rather than the simple voltage or current was measured, because the body presents a complex impedance to the current. The total impedance, when the electrodes are applied in a standard manner, decreases with increasing frequency. The power factor varies slightly with frequency. When the power is increased about 20 db above the threshold value, the threshold of electric shock—a stinging sensation—is reached. This effect severely limits the size of the auditory area under electrical stimulation. The amount of distortion present makes it difficult to understand speech when the observer is connected directly to the output circuit of a radio set, but music can be readily identified. The rectification producing this distortion appears to be largely electrical. It is probable that the alternating current sets up vibrations in the inner ear due, perhaps, to a residual charge on the basilar membrane which makes it behave as a condenser microphone.