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In this paper, the use of non-uniform ac electric fields on biological cells for bioanalysis, through multiple, independently configurable channels is presented. The programmable system has been used to obtain the dielectrophoretic spectra of cells in near real time, within 90 seconds. This is a significant improvement on existing dielectrophoretic techniques as simultaneous parallel measurement of...
In neurophysiological and pharmaceutical research, parallel and individual access to a dense population of in-vitro cultured neurons is a key feature for analyzing networks of neurons. This paper presents a 0.18μm CMOS chip containing a dense array of micro-nail electrodes, a 128 × 128 sensor/actuator matrix with in-situ differential amplification circuits, pico-Ampere current stimulation, and impedance...
Non-thermal irreversible electroporation (N-TIRE) is a new minimally invasive technique to kill undesirable tissue. We build on our previous intracranial studies in order to evaluate the possibility of using N-TIRE for deep intracranial disorders. In this manuscript we describe a minimally invasive computed tomography (CT) guided N-TIRE procedure in white matter. In addition, we report the electric...
Deep brain stimulation (DBS) therapy relies on electrical stimulation of neuronal elements in small brain targets. However, the lack of fine spatial control over field distributions in current systems implies that stimulation easily spreads into adjacent structures that may induce adverse side-effects. This study investigates DBS field steering using a novel DBS lead design carrying a high-resolution...
We have developed a novel 4-channel prototype stimulation circuit for implantable neurological stimulators (INS). This Switched-Capacitor based Stimulator (SCS) aims to utilize charge storage and charge injection techniques to take advantage of both the efficiency of conventional voltage-controlled stimulators (VCS) and the safety and controllability of current-controlled stimulators (CCS). The discrete...
Functional electrical stimulation (FES) refers to the method by which sensory or motor functionality is restored through the use of coordinated stimulation of tissue. Our group has developed a mechanically conformable multielectrode array (cMEA) that can stimulate and record from the surface of muscles with high fidelity and low invasiveness, making the device well suited for various FES applications...
This work is an assistive technology for people with visual disabilities and aims to facilitate access to written information in order to achieve better social inclusion and integration into work and educational activities. Two methods of electrical stimulation (by current and voltage) of the mechanoreceptors was tested to obtain tactile sensations on the fingertip. Current and voltage stimulation...
The aim of this study is to develop a method for measuring the respiratory waveform using non-contact electrodes during bathing. To determine the most appropriate electrode arrangement, we modeled a composite system consisting of a body submerged in bath water. We calculated the frequency dependence of the impedance amplitude using a three-dimensional finite difference method (3D-FDM). The simulation...
Electrocorticographic recording is now being used in a wide variety of experimental settings. We present a simple method which can be used to estimate electrode position with respect to brain gyral anatomy using a pre-implantation MRI and post-implantation coronal and sagittal x-rays. It is semi-automated, with the user manually rotating and scaling an x-ray to fit brain outline, identifying threshold...
Electrical stimulation of the optic nerve with penetrating electrode array for visual recovery had been proposed by C-Sight group. This paper presents the latest progress of various component parts of visual prosthesis, including design and testing of neural stimulator, fabrication of multi-channel flexible microelectrode array. According to the experiment data, the linearity between practical stimulator...
This paper analyses the use of Electrical Impedance Spectroscopy (EIS) to efficiently monitor cryoprotectant concentrations in cryopreservation protocols. The proposed technique can improve methods such as Liquidus Tracking (LT), allowing vitrification without exposing tissues to damaging concentrations of cryoprotectant at relatively high temperatures, and avoiding rapid temperature changes. This...
Irreversible electroporation (IRE) has shown promise for the therapeutic treatment of focal disease, including tumors. The effects of treatment are dependent on the electric field distribution, which may be predicted with numerical modeling. In order to improve the effectiveness and scope of IRE therapies, techniques must be developed for designing protocols capable of treating large and irregular...
We present a novel method for monitoring sympathetic nervous system activity during epileptic seizures using a wearable sensor measuring electrodermal activity (EDA). The wearable sensor enables long-term, continuous EDA recordings from patients. Preliminary results from our pilot study suggest that epileptic seizures induce a surge in EDA. These changes are greater in generalized tonic-clonic seizures...
Much of our knowledge about the electric field distribution in transcranial current stimulation (tCS) still relies on results obtained from layered spherical head models. In this work we created a high resolution finite element model of a human head by segmentation of MRI images, and paid particular attention to the representation of the cortical sheet. This model was then used to calculate the electric...
Interest in the electrical modeling of the thorax is motivated by various desires ranging from determining cardiac function, optimizing defibrillation efficacy, monitoring pulmonary edema, etc. However, existing models represent the thorax with rather coarse anatomical details, limiting their utilizations for accurately simulating small electrodes which typically occurs in pacing and defibrillation...
The goal of this study is to investigate the regional distribution of the electric field (E-field) strength induced by electroconvulsive therapy (ECT), and to contrast clinically relevant electrode configurations through finite element (FE) analysis. An FE human head model incorporating tissue heterogeneity and white matter anisotropy was generated based on structural magnetic resonance imaging (MRI)...
We performed optical intrinsic signal imaging of cat primary visual cortex (Area 17 and 18) while delivering bipolar electrical stimulation to the retina by way of a supra-choroidal electrode array. Using a general linear model (GLM) analysis we identified statistically significant (p <;; 0.01) activation in a localized region of cortex following supra-threshold electrical stimulation at a single...
In this article, we present a functional electrical stimulator allowing the extraction in real time of M-wave characteristics from resulting EMG recordings in order to quantify muscle fatigue. This system is composed of three parts. A Labview software managing the stimulation output and electromyogram (EMG) input signal, a hardware part amplifying the output and input signal and a link between the...
The safety of electroconvulsive therapy (ECT) in patients who have deep brain stimulation (DBS) implants represents a significant clinical issue. A major safety concern is the presence of burr holes and electrode anchoring devices in the skull, which may alter the induced electric field distribution in the brain. We simulated the electric field using finite-element method in a five-shell spherical...
Direct current (DC) ablation is a novel non-thermal technology that causes focused coagulative necrosis in the lateral lobes of the prostate to treat benign prostatic hyperplasia (BPH). The necrosis is caused by a zone of non-physiologic pH which is created in a predictable pattern around each electrode in which a direct current is applied during treatment. The objective of this study was to optimize...
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