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Electrophysiology
Published in A. Bakiya, K. Kamalanand, R. L. J. De Britto, Mechano-Electric Correlations in the Human Physiological System, 2021
A. Bakiya, K. Kamalanand, R. L. J. De Britto
Microelectrodes consist of an ultrafine-tapered tip and are used for either signal acquisition in single cells or electrical stimulations of nerve tissues (Plieth, 2008). The electrode tip must be small when compared to the cell dimension to avoid cell damage and to enable easy penetration into the cell wall. There are three categories of microelectrodes namely, glass micropipettes, metal microelectrodes and solid-state microprobes (Enderle & Bronzino, 2012), as shown in Figure 3.4. Mostly, solid-state microelectrodes are used for multi-channel recordings of biopotential or electrical stimulation of neuron cells in brain or spinal cord (Enderle & Bronzino, 2012; Manahan-Vaughan, 2018). The major advantage of using solid-state microelectrodes instead of other two microelectrode types is the capability to manufacture small size electrodes in a mass quantity.
Trends in Polymer Applications
Published in Manas Chanda, Plastics Technology Handbook, 2017
Microelectrode neural probes facilitate the functional stimulation or recording of neurons in the central nervous system and peripheral nervous system. Minimizing the electrode impedance is an important requirement for obtaining high quality signals (high signal-to-noise ratio). It has been shown [72,73] that conducting polymers such as polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) can decrease the impedance of the recording electrode sites on neural prosthetic devices. It has also been demonstrated [74] that the impedance of the neural microelectrodes can be further decreased significantly (by about two orders of magnitude) and the charge-transfer capacity significantly increased (about three orders of magnitude) by creating conducting polymer nanotubes on the microelectrode surface. The conducting nanotubes that have well-defined internal and external surface texture decrease the electrode impedance by increasing the effective surface area for ionic-to-electronic charge transfer to occur at the interface between brain tissue and the recording site. The drugs can be released from the (drug-loaded) conducting nanotubes at desired points in time by using external electrical stimulation of the nanotubes. This process presumably proceeds by a local dilation of the tube that then promotes mass transport.
Microsupercapacitors
Published in Ling Bing Kong, Nanomaterials for Supercapacitors, 2017
Ling Bing Kong, Wenxiu Que, Lang Liu, Freddy Yin Chiang Boey, Zhichuan J. Xu, Kun Zhou, Sean Li, Tianshu Zhang, Chuanhu Wang
The microsupercapacitors had 32 in-plane interdigital Au microelectrodes, 16 positive and 16 negative microelectrodes. The individual microelectrode had a width of 230 μm, a length of 10 mm and a finger distance of 200 μm. Figure 7.43(a) shows SEM image of the planar interdigital microsupercapacitor, suggesting that the GQDs had been uniformly coated on the Au electrodes. The deposited GQDs aggregated to form nanoparticles, as illustrated in Fig. 7.43(b, c). Figure 7.43(d) shows cross-sectional SEM image of the Au microelectrode, revealing that the layer of GQDs had a thickness of 312 nm. Meanwhile, the GQDs layer had an intimate contact with the Au-electrode.
Deep Brain Stimulation Coding in Parkinson’s: An Evolving Approach
Published in IETE Journal of Research, 2021
Dabbeta Anji Reddy, Venkateshwarla Rama Raju, G. Narsimha
DBS is one therapeutic surgical method for Parkinson’s which employs high-frequency electrical pulses for STN stimulus and connected brain areas. The implanted device sends electrical signals/pulses to the areas of the brain responsible for body movement that reduces tremors and restores motor functioning in subjects with advanced Parkinson’s disease. The microelectrodes are embedded deep in the brain and connected to a stimulating device (the electric circuit around the neck which sends the impulses to the microelectrode) and the circuit is charged by a device that can resemble a cardiac pace maker; a neurostimulator uses electric pulses control and/or regulates the brain. The DBS can reduce the features, i.e. PD symptoms of tremor, slowness of movement, stiffness and gait disability caused by the PD, resting tremor (RT), and other movement dystonic (dystonia) disorders. The microelectrodes are used to record neuronal activity and macroelectrodes are used to record the local field potentials (LFPs). Both methods are effective in treating middle- and late-stage PD, showing progression in quality of life (QoL) and motoric features by diminishing the impediments of mounting quantity of drug use [11].
A Functional BCI Model by the P2731 working group: Physiology
Published in Brain-Computer Interfaces, 2021
Ali Hossaini, Davide Valeriani, Chang S. Nam, Raffaele Ferrante, Mufti Mahmud
The use of electrodes to interface with the nervous system began with Luigi Galvani’s experiments on frogs in the late 18th century. In the 20th century, it became practical to implant electrodes into living human brains to both record and stimulate mental activity. While the first implants recorded a locality of multiple neurons, for decades it has been possible to insert electrodes called ‘patch clamps’ into a single neuron using either metal filaments or a glass pipette filled with a conductive fluid [36]. Whether implanted directly into a neuron or recording the activity of a local population, microelectrodes have facilitated enormous progress in neurophysiology and the disciplines which depend on it. Because they can be inserted with precision, implants enable BCI applications to tap the cerebral regions most appropriate to the required output, e.g. control of movement or speech.