Set Of Electrodes Research Articles

An 8-Bit Digitally Operated Micromachined Accelerometer

This work presents successful implementation and characterization of an 8-bit digitally operated micromachined accelerometer. Such device is comprised of an electrostatically tunable acceleration switch with 8 sets of electrostatic tuning electrodes. Similar to bits in a binary number, the tuning force of each electrode set increases by a factor of 2 with respect to the adjacent electrode set. A fabricated device has been interfaced with a micro-controller performing a binary search by controlling state of different tuning electrodes (ON or OFF) to interpret the acceleration with 8 bits of resolution. Measurement results show good agreement between the applied acceleration and the binary acceleration output of the sensor reported by the controller. The tested 8-bit prototype has full-scale acceleration of 2.7g with resolution 10.5 mg s (1/28 of full scale). Requiring only a bias voltage for operation (zero static current) and readout of the switch output (a digital high or low voltage) that can be performed directly by a digital controller, such devices can lead to ultra-low power accelerometers by eliminating the need for an analog-front-end. [2020-0201]

Physical vapor deposition using a coaxial ion acceleration method.

A novel physical vapor deposition method involving electromagnetic acceleration using a set of coaxial electrodes has been developed. In this study, the coaxial ion acceleration method is applied for a diamond-like carbon (DLC) thin film formation. In the developed method, the central electrode made of the deposition material is sputtered by the noble gas plasma current and accelerated toward the deposition chamber. Because the sputtered ions are accelerated by the Lorentz self-force, the ion injection energy can be controlled separately from the plasma temperature. In addition, the gaseous hydrocarbon, which is commonly used for DLC formation, is not required since a noble gas is used as the discharge gas.

Combined FIM-PHI-Based Wearable Biosensor

Focused impedance method (FIM) is a simple non-invasive way of diagnosing epidermal tissue health by subsequent measurements of localized impedance using a set of tetra-polar orthogonal electrodes. The concept is further advanced to an increased number of electrodes with repeated FIM cells that combinedly form a pigeon hole image (PHI) and used to diagnose a range of physiological conditions and disorders. In this work, a wearable imaging device has been demonstrated by combining the attributes of FIM-based pigeon hole imaging and utilised them for detecting unusual body mass within a biological system. The device uses a total of twenty-five Cu electrodes uniformly distributed over a spatial area <inline-formula> <tex-math notation="LaTeX">${A} = 16$ </tex-math></inline-formula> cm² which combinedly form the 16 elements of a <inline-formula> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> PHI matrix. The PHI device is capable to produce a 2D crude image of bio-impedance with a pixel resolution of 1 cm and visualise an unusual body mass underneath the testing surface at depth, <inline-formula> <tex-math notation="LaTeX">${d}_{p} \sim 0.3$ </tex-math></inline-formula> to 2.0 cm. The ubiquitous functionality of the device has been demonstrated by integrating into a custom made flexible fabric as wearable wrist band that measures the PHI image and recognizes three common gesture positions using a well-known artificial neural network classifier. The wearable device can be an emerging telemedicine solution for rapid screening of a range of abnormal physiological phenomenon at patient&#x2019;s home or in a regional hospital with resource limited settings.

Optimization of a wearable speed monitoring device for welding applications

The heat input is a parameter used to ensure quality of submerged metal arc welding, one of the most common metal joining procedures in the manufacturing industry. This parameter is dependent on the current and voltage, defined by the specific welding procedure, along with the welding speed, a feature that is strongly dependent on the hand movement of the welding operator. A wearable speed monitoring device (SMD) was developed by fusing optical and inertial sensor data to measure the handheld device speed of the welder. This work aims at tuning the parameters affecting the performance of SMD prototype by testing it with four batches of common electrodes in a real industrial environment. The outcomes were compared with the results from the traditional manual calculation, namely, a true coarse average (TCA) velocity. At first, observations were performed to identify any scope of improvement for the SMD. Secondly, an optimization of the main parameters was performed by minimizing a cost function involving the TCA velocities for each batch. A final assessment was then performed with the optimized parameters evaluating the achieved results; a comparative analysis showed a reduction of the relative average errors of 32%, 1.4%, and 4.2% for 2.5, 4, and 5 mm electrode sets, respectively. The system was found already optimized for the 3.25-mm electrodes, using baseline parameters with an error of about 12%. The methodology employed in this study can be further utilized in scenarios in which speed monitoring is employed for light-driven applications with a moving reference.

A silver/silver chloride woven electrode with convex based on electrical impedance tomography

Advanced wearable medical devices are widely used for health monitoring, i.e. recording and analyzing signals from human organs. However, the signal quality is influenced significantly by medical electrodes, which became the bottleneck for health monitoring due to unstable impedance under long-term daily usage. Here, a novel monitoring electrode was designed with uniform micro-convex shape to increase the impedance reliability of electrode-skin interface in long-term monitoring and under dynamic conditions, and we set up the electrode-skin interface model to describe the electrode-skin interface and impedance distribution clearly. Furthermore, we investigated how the electrodeposition factors affect the electrode deposition uniformity and electrode resistance. In this study, we compared the monitoring performance among two sets of electrodes: 1) Ag electrodes and Ag/AgCl electrodes, 2) plain Ag/AgCl electrodes, jacquard Ag/AgCl electrodes, and commercial wet electrodes. Specifically, the monitoring performance was quantified by the electrode-skin interface impedance during long-term monitoring, under different dynamic conditions. The optimal electrodeposition process was a ‘small step’ multi-potential method with the 1-1.5-2 V mode. The jacquard Ag/AgCl electrodes presented the best monitoring performance under all three measurement scenarios across four types of electrodes. The results indicated that the proposed electrodes could be used for long-term medical monitoring under daily life activities based on electrical impedance tomography.

Development of a two-dimensional piezoelectric traveling-wave generator

In this article, we present a new method to control the direction of traveling waves in either an x-direction or y-direction on a two-dimensional square plate. The core structure was composed of a piezoelectric serial bimorph with four electrodes. Each electrode was spatially designed to activate one of the bending modes and which included the ability to reduce adjacent modes and minimize interference. Our new method differs from other reported methods in that the four electrodes were driven at designated resonant frequencies. In our wave generator, different driving amplitudes and phases were applied to induce the traveling waves to propagate in a specific direction. To design the directional movement and to better understand the pattern of induced traveling waves, an analytical solution was derived to assist in the design of the four driving electrodes. Using our newly developed analytical method, traveling waves can be controlled to travel in either the x-direction or y-direction using two different sets of electrodes, where each electrode can be driven at a specific but different bending mode. We found that both the voltage ratio and phase difference between the two driving electrodes are important factors for optimization.

FeNi3 and Ni-Based Nanoparticles as Electrocatalysts for Magnetically Enhanced Alkaline Water Electrolysis

Today, hydrogen mainly originates from fossil sources (gas, oil, and coal). Room temperature water electrolysis is an interesting alternative for renewable electricity storage, even if it is well-known that high-temperature systems are more efficient. To address this issue, we studied different non-platinum group metal (non-PGM) catalysts for alkaline oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) by recording cyclic voltamperograms with a rotating disk electrode set up. Physicochemical characterizations of Ni-based and FeNi3-based catalysts were performed using transmission electron microscopy, X-ray diffraction (XRD), and inductively coupled plasma mass spectroscopy (ICP-MS). Ni synthesized by the hot injection method is a good catalyst for HER, yet still less active than Pt/C. FeNi3 with and without a Ni surface doping is very good OER catalysts, slightly better than commercial unsupported IrO2. Electrochemical tests under alternating magnetic field (AMF) using these nanoparticles are ongoing, as these materials are compatible with AMF activation.

Woven electrocardiogram (ECG) electrodes for health monitoring in operational environments.

Electrical signals produced within the human body can reveal information about a wide variety of physiological processes including physical activity, cardiac health, and psychological state. The industry standard for physiological signal detection is the use of adhesive electrodes that stick onto the skin. These electrodes can irritate the skin over long periods of time and are not reusable, making them a challenge for use in operational environments. Further, these electrodes often require gel to improve signal transduction, leading to changes in signal quality as these gels dry over time. Wearable sensors for operational environments should be comfortable, unobtrusive, and non-stigmatizing while maintaining signal quality high enough to allow the detection of health states. Here, we present the development and test of a set of woven textile electrodes of 8 different sizes for chest-mounted, 3-lead electrocardiogram (ECG) monitoring. Ten male subjects were tested with each of the woven electrode sizes and with one set of adhesive electrodes. A derived performance metric and signal-to-noise ratio were calculated for each set of electrodes for comparison between them. The smallest sized electrodes were found to be least effective, while the 6th of the 8 sizes were found to be most effective.

The Effects of Channel Number on Classification Performance for sEMG-based Speech Recognition.

Speech recognition based on surface electromyography (sEMG) signals is an important research direction with potential applications in life, work and clinical. The number and placement of sEMG electrodes play a critical role in capturing the underlying sEMG activities and in turn, accurately classifying the speaking tasks. The aim of this work was to investigate the effect of the number of channels in speech recognition based on high-density (HD) sEMG. 8 healthy subjects were recruited to perform 11 English speech tasks with sEMG signals were detected from 120 electrodes covering almost the whole neck and face. The classification accuracy was evaluated in the context of a linear discriminant analysis (LDA) with different sets of EMG electrodes. By comparing the classification accuracy, the sequential forward search (SFS) algorithm was adopted to figure out the optimal combination of electrodes which realized the highest classification level. The results showed that smaller number of channels obtained by the SFS method could achieve the classification accuracy of 80%, and another few electrodes were needed to record detail information to achieve the classification accuracy of 85%, 90% and 95%. The numbers were rather smaller than 120. Considering the computation time and reliable accuracy, it is concluded that the SFS method might be helpful for standardizing the number and position of electrodes in speech recognition.

Dielectrophoretic Microfluidic Device for Separating Microparticles Based on Size with Sub-Micron Resolution.

This article details the mathematical model of a microfluidic device aimed at separating any binary heterogeneous sample of microparticles into two homogeneous samples based on size with sub-micron resolution. The device consists of two sections, where the upstream section is dedicated to focusing of microparticles, while the downstream section is dedicated to separation of the focused stream of microparticles into two samples based on size. Each section has multiple planar electrodes of finite size protruding into the microchannel from the top and bottom of each sidewall; each top electrode aligns with a bottom electrode and they form a pair leading to multiple pairs of electrodes on each side. The focusing section subjects all microparticles to repulsive dielectrophoretic force, from each set of the electrodes, to focus them next to one of the sidewalls. This separation section pushes the big microparticles toward the interior, away from the wall, of the microchannel using repulsive dielectrophoretic force, while the small microparticles move unaffected to achieve the desired degree of separation. The operating frequency of the set of electrodes in the separation section is maintained equal to the cross-over frequency of the small microparticles. The working of the device is demonstrated by separating a heterogeneous mixture consisting of polystyrene microparticles of different size (radii of 2 and 2.25 μm) into two homogeneous samples. The mathematical model is used for parametric study, and the performance is quantified in terms of separation efficiency and separation purity; the parameters considered include applied electric voltages, electrode dimensions, outlet widths, number of electrodes, and volumetric flowrate. The separation efficiencies and separation purities for both microparticles are 100% for low volumetric flow rates, a large number of electrode pairs, large electrode dimensions, and high differences between voltages in both sections.

Entropy-Based Estimation of Event-Related De/Synchronization in Motor Imagery Using Vector-Quantized Patterns.

Assessment of brain dynamics elicited by motor imagery (MI) tasks contributes to clinical and learning applications. In this regard, Event-Related Desynchronization/Synchronization (ERD/S) is computed from Electroencephalographic signals, which show considerable variations in complexity. We present an Entropy-based method, termed VQEnt, for estimation of ERD/S using quantized stochastic patterns as a symbolic space, aiming to improve their discriminability and physiological interpretability. The proposed method builds the probabilistic priors by assessing the Gaussian similarity between the input measured data and their reduced vector-quantized representation. The validating results of a bi-class imagine task database (left and right hand) prove that VQEnt holds symbols that encode several neighboring samples, providing similar or even better accuracy than the other baseline sample-based algorithms of Entropy estimation. Besides, the performed ERD/S time-series are close enough to the trajectories extracted by the variational percentage of EEG signal power and fulfill the physiological MI paradigm. In BCI literate individuals, the VQEnt estimator presents the most accurate outcomes at a lower amount of electrodes placed in the sensorimotor cortex so that reduced channel set directly involved with the MI paradigm is enough to discriminate between tasks, providing an accuracy similar to the performed by the whole electrode set.

Measurement of Effective Area of Metallization at Galvanic Processes

Рассмотрены особенности измерения площади проводящих покрытий сложных топологий в процессе гальванической металлизации. Показано, что при разработке и исследовании гибридных слоистых структур наиболее сложно оценивать эффективную площадь проводящих металлических и неорганических поверхностей и электродов. Проведен анализ применимости разнообразных способов расчета и моделирования при проектировании проводящих поверхностей в условиях сложной топологии электрического поля и множества влияющих факторов. Установлено, что доминирующие в настоящее время оптические методы не обеспечивают требуемой достоверности контроля эффективной площади проводящих поверхностей. Доказано, что только применение ионного потока позволяет измерять площадь покрытия с учетом топологии электрического поля металлизируемой поверхности. Выбран принцип измерения среднегеометрической площади гальванопары на основе ее зависимости от отношения эквивалентной проводимости гальванической цепи к удельной проводимости электролита. Разработан алгоритм, позволяющий экспериментально определять площадь металлизации изделия Sk, в котором коррекция результата измерения площади катода на топологию линий тока и краевые поля металлизируемой поверхности выполняется автоматически.Выбраны измерительные преобразователи: ток I – напряжение UI, напряжение U – напряжение UU и корректирующие преобразования контактной разности потенциалов, средней длины линий тока и обратной площади анода в нормированные напряжения. Определены условия и критерии нормировки и согласования с аналого-цифровыми преобразователями. На выходе аналого-цифрового преобразователя формируются коды тока NI, напряжения NU и соответствующих параметров процесса измерительного преобразования.Синтезирована структурная схема измерительного преобразователя площади металлизации. Она состоит из измерительно-установочного блока и процессора. Изделие – катод, анод и набор электродов-датчиков – помещается в ванну с электролитом. Источник питания создает в ванне постоянный ток, который измерительными преобразователями преобразуется в коды напряжения, тока, удельной проводимости, контактной разности потенциалов, средней длины линий тока и обратной площади анода. Процессор реализует алгоритм измерительного преобразования и формирует измерительный сигнал USk, пропорциональный эффективной площади изделия Sk и (или) код NSk. Показано, что возможна автоматизация измерительного преобразования в режимах питания гальванических установок импульсным и импульсно-реверсивным токами. В режиме импульсного питания предложено в блоки, работающие в импульсном режиме, вводить интеграторы. В импульсно-реверсивном режиме в эти блоки должны вводиться корреляционные фильтры.Разработана схема измерительной установки для измерения площади электропроводных деталей в процессе металлизации в импульсном и импульсно-реверсивном режимах. Включение синтезированных измерителей в состав систем автоматического управления током гальванических ванн обеспечивает уменьшение расхода материалов, экономию электрической энергии, повышение уровня автоматизации нанесения покрытий.

Modeling a Dielectrophoretic Microfluidic Device with Vertical Interdigitated Transducer Electrodes for Separation of Microparticles Based on Size.

This article conceptualizes and mathematically models a dielectrophoretic microfluidic device with two sets of interdigitated transducer vertical electrodes for separation of a binary heterogeneous mixture of particles based on size; each set of electrodes is located on the sidewalls and independently controllable. To achieve separation in the proposed microfluidic device, the small microparticles are subjected to positive dielectrophoresis and the big microparticles do not experience dielectrophoresis. The mathematical model consists of equations describing the motion of each microparticle, fluid flow profile, and electric voltage and field profiles, and they are solved numerically. The equations of motion take into account the influence of phenomena, such as inertia, drag, dielectrophoresis, gravity, and buoyancy. The model is used for a parametric study to understand the influence of parameters on the performance of the microfluidic device. The parameters studied include applied electric voltages, electrode dimensions, volumetric flow rate, and number of electrodes. The separation efficiency of the big and small microparticles is found to be independent of and dependent on all parameters, respectively. On the other hand, the separation purity of the big and small microparticles is found to be dependent on and independent of all parameters, respectively. The mathematical model is useful in designing the proposed microfluidic device with the desired level of separation efficiency and separation purity.

Electrophysiological Evidence for Distinct Proactive Control Mechanisms in a Stop-Signal Task: An Individual Differences Approach.

Proactive control reflects a sustained, top-down maintenance of a goal representation prior to task-related events, whereas reactive control reflects a transient, bottom-up goal reactivation in response to them. We designed a manual stop-signal task to isolate electrophysiological signals specifically involved in proactive control. Participants performed a simple choice reaction time task but had to withhold their response to an infrequent stop signal, resulting in go- and stop-signal trials. We manipulated the stop-signal probability (30% vs. 10%) over different blocks of trials so that different proactive control levels were sustained within each block. The behavioral results indicated that most participants proactively changed their behaviors. The reaction times in the go trials increased and the number of response errors in the stop-signal trials decreased. However, those two behavioral measures did not correlate: individuals with an increased delayed reaction did not necessarily manifest a higher decrease in response errors in the stop-signal trials. To isolate the proactive control signal, we obtained event-related potentials (ERPs) locked to an uninformative fixation onset and compared the signals between the two stop-signal probability conditions. We found that the ERPs at the left hemisphere were more negatively shifted with the increasing stop-signal probability. Moreover, ERP differences obtained from a set of electrodes in the left hemisphere accounted for the changes in response errors in the stop-signal trials but did not explain the changes in reaction times of the go trials. Together, the behavioral and electrophysiological results suggest that proactive control mechanisms reducing erroneous responses of the stop-signal trials are different from mechanisms slowing reaction times of the go trials.

A miniaturized capacitive absolute angular positioning sensor based on a dual two-stage secondary re-modulation Scheme with time-division multiplexing

This paper proposes a new capacitive absolute angular positioning sensor based on time grating that adopts two capacitor arrays, each employing a two-stage secondary re-modulation scheme, where the output signals from the first-stage induction electrodes are applied as the excitation signals to the second-stage excitation electrodes to generate second-stage induction electrode outputs with respective periodicities of N+1 and N+2. This enables the capture of high precision absolute angular measurements according the principle of Vernier calipers, where the N+2 period output signal is employed for obtaining fine measurements, while the phase difference between the output signals is employed for absolute positioning. Sensor miniaturization is facilitated by sharing the outputs of the first-stage capacitor arrays with a single second-stage capacitor array using time division multiplexing, which eliminates the need for a second second-stage capacitor array by alternately applying the excitation signals to the two sets of first-stage electrodes. Measurement performance is evaluated experimentally by testing a prototype sensor fabricated by printed circuit board processing with an outer diameter of 83 mm and an inner diameter of 24 mm. The experimental results demonstrate a peak-to-peak measurement error of about 30″ over the 360° measurement range.

Designs of Experiments to Optimize Li-Ion Batteries

Studies pinpointed the limitation of power-related performance for Li-ion batteries to the microstructure of each electrode.1, 2 This random arrangement of the active material (AM) and carbon filling particles bound by a polymer is typically characterized through physical values such as tortuosity, porosity and Mac Mullin Number.3 There is nonetheless no consensus on what the best formulation is for a given set of electrode components.The relationship between microstructure and performance is investigated by planning and analyzing a Design of Experiments based on a Complex Mixture Design. Thirty different formulations were characterized where Li4Ti5O12 was the AM, and carbon black and carbon nanofibers were conductive fillers. As for the binder, two were studied: polyvinylidene fluoride and a fluorine-free thermoplastic elastomer.4 All other factors, e.g. rheology or experimenter bias, were closely monitored and finely controlled to remain identical for all samples.Electrochemical performance were studied at low, medium and high charging speeds to account for different limitations of full capacity retention. Statistical analysis showed clear correlations between the formulation and the electrodes’ capacity with very high descriptive statistics, e.g. R2. Lastly, strong correlations were found between capacity and microstructure, strengthening further the trust in the empirical equations. These robust models helped choosing optimal fluorine-free formulations that surpassed even the highest performing previous electrodes. 1. Vasileiadis, A.; Klerk, N. J. J. d.; Smith, R. B.; Ganapathy, S.; Harks, P. P. R. M. L.; Bazant, M. Z.; Wagemaker, M., Toward Optimal Performance and In‐Depth Understanding of Spinel Li4Ti5O12 Electrodes through Phase Field Modeling. Advanced Functional Materials 2018, 0 (0), 1705992.2. Ngandjong, A. C.; Rucci, A.; Maiza, M.; Shukla, G.; Vazquez-Arenas, J.; Franco, A. A., Multiscale Simulation Platform Linking Lithium Ion Battery Electrode Fabrication Process with Performance at the Cell Level. The Journal of Physical Chemistry Letters 2017, 8 (23), 5966-5972.3. Landesfeind, J.; Hattendorff, J.; Ehrl, A.; Wall, W. A.; Gasteiger, H. A., Tortuosity Determination of Battery Electrodes and Separators by Impedance Spectroscopy. Journal of The Electrochemical Society 2016, 163 (7), A1373-A1387.4. Rynne, O.; Lepage, D.; Aymé-Perrot, D.; Rochefort, D.; Dollé, M., Application of a Commercially-Available Fluorine-Free Thermoplastic Elastomer as a Binder for High-Power Li-Ion Battery Electrodes. Journal of The Electrochemical Society 2019, 166 (6), A1140-A1146.With this presentation, we want to show the versatility and power of Designs of Experiments to the community, whether for electrode formulation or new material synthesis, as the input parameters can be easily interchangeable. Figure 1

Schizophrenia Detection Using Biomarkers from Electroencephalogram Signals

Schizophrenia is an incurable neurological disorder that changes human being’s perception and behavior due to genetic and environmental factors. The objective of this study is to detect Schizophrenia using electroencephalogram signals as biomarker. In this work, two time-domain features, namely Higuchi Fractal Dimension and correlation from a pair of electrodes have been extracted. In addition, two time-domain statistical features i.e., mean and variance are also computed. Analysis has been carried out from each electrode to identify a set of potential electrodes for the detection of schizophrenia to reduce the computational complexity. The algorithm has been validated using leave-one-out strategy and the results obtained show an accuracy of 100%. Also the result has been validated with topographic maps of identified electrodes.

A Method to Enhance Stroke Level of a MEMS Micromirror with Repulsive Electrostatic Force.

This paper presents a method to enhance the stroke level of a MEMS micromirror that, unlike conventional micromirrors, is actuated using a repulsive electrostatic force. The designed and proposed micromirror is held by L-shaped arms suspended over a set of bottom electrodes. In this configuration, three bottom electrodes are centered below each arm and are separated with a designed gap from each other to optimize the generated repulsive force. Using this approach, the micromirror surface is forced to deflect upward compared with the conventional downward deflection. The designed micromirror is proposed to utilize the PolyMUMPs fabrication technique from MEMSCAP Inc. In this work and in an unconventional approach, an air cavity of 2.75 µm can be achieved by combining the two available oxide layers through an additional removal of a polysilicon structural layer. It is shown that this design can significantly enhance the stroke level of the proposed micromirror to 5 µm at 150 V DC.

SPARC: Current Steering To Selectively Recruit Nerves Of The Lower Urinary Tract

Lack of bladder control has a substantial impact on quality of life, with consequences ranging from sleep deprivation and embarrassment to bladder and kidney infection. Current methods to address lower urinary tract (LUT) dysfunction, including pharmacological interventions and catheterization, are insufficient to restore bladder control and may lead to rehospitalization, especially after spinal cord injury. Previously, we have used epidural spinal cord stimulation (SCS) to selectively recruit nerves innervating the LUT, a promising result that suggests this method of stimulation could be used to address LUT dysfunction. Epidural SCS has been in use clinically for pain relief for over 50 years, and is a minimally‐invasive way to access these neural pathways. However, current clinical leads have large electrodes that make it difficult to spatially limit the region targeted by SCS. Here, we use a high‐density epidural spinal cord electrode and multipolar stimulation patterns to reduce off‐target neural recruitment and refine the selective activation of LUT nerves.We placed a high‐density epidural spinal cord electrode (MicroLeads Inc) at three locations of the sacral spinal cord and cauda equina in cats under isoflurane anesthesia. To record antidromic compound action potentials evoked by SCS, we recorded from nerve cuffs (MicroLeads Inc) on the sciatic nerve, pelvic nerve, as well as the pudendal nerve and its branches. To measure muscle recruitment during stimulation, we recorded electromyogram (EMG) activity from the external urethral sphincter, external anal sphincter, pelvic floor and gluteus. Using catheters in the bladder and urethra, we measured pressure changes during stimulation. We stimulated on all electrodes of the spinal cord arrays individually, as well as in bipolar and tripolar sets of electrodes to determine the effect of current steering on LUT nerve recruitment.We were able to recruit LUT nerves with all configurations of stimulation electrodes. However, monopolar stimulation resulted in substantial selective recruitment of the off‐target sciatic nerve, representing 59% of selective responses at the most rostral sacral location, 72% at the more caudal sacral location, and 27% at the cauda equina. By using bipolar and tripolar stimulation across the same electrodes, we were able to steer current so that electrodes selective for the sciatic nerve with monopolar stimulation were selective for LUT responses. Additionally, recruitment thresholds of monopolar stimulation were typically lower, between 50–1000 μA, than those of multipolar stimulation, which ranged from 100–2800 μA. We were also able to change the EMG recruitment with changes in electrode configurations, allowing targeting of functionally‐relevant muscles.We were able to map the recruitment of LUT nerves and muscles across several levels of the spinal cord using both monopolar and multipolar stimulation. By using these stimuli to access LUT nerves and muscles, we hope to systematically modify function in the LUT, providing a potential route to treat LUT dysfunction.Support or Funding InformationNIH SPARC award 1OT2OD024908 and Craig H. Neilsen Foundation, award 476681

Model-based design for seizure control by stimulation

Objective. Current brain stimulation paradigms are largely empirical rather than theoretical. An opportunity exists to improve upon their modest effectiveness in closed-loop control strategies with the development of theoretically grounded, model-based designs. Approach. Inspired by this need, here we couple experimental data and mathematical modeling with a control-theoretic strategy for seizure termination. We begin by exercising a dynamical systems approach to model seizures (n = 94) recorded using intracranial EEG (iEEG) from 21 patients with medication-resistant, localization-related epilepsy. Main results. Although each patient’s seizures displayed unique spatial and temporal patterns, their evolution can be parsimoniously characterized by the same model form. Idiosyncracies of the model can inform individualized intervention strategies, specifically in iEEG samples with well-localized seizure onset zones. Temporal fluctuations in the spatial profiles of the oscillatory modes show that seizure onset marks a transition into a regime in which the underlying system supports prolonged rhythmic and focal activity. Based on these observations, we propose a control-theoretic strategy that aims to stabilize ictal activity using static output feedback for linear time-invariant switching systems. Finally, we demonstrate in silico that our proposed strategy allows us to dampen the emerging focal oscillatory sources using only a small set of electrodes. Significance. Our integrative study informs the development of modulation and control algorithms for neurostimulation that could improve the effectiveness of implantable, closed-loop anti-epileptic devices.