Electrical stimulation, electrode muscles

A heart muscle cell (rabbit cardiomyocyte) was aligned in a narrow PDMS-glass microchannel. The muscle cell was electrically stimulated via a pair of Au electrodes ( 60 pm apart) in contact with the cell. Intracellular Ca measurement showed that the cell remained contracted for 60 min within the restricted space. An electric field strength of 20 V/cm translates to 0.12 V, which is lower than the electrolysis threshold of 0.8 V [834]. 

While electrodes may be integrated as detectors, another possibility is to use the electrodes to stimulate muscles. Electrodes for functional electrical stimulation have been integrated into fabrics to provide actuation stimuli to muscles of the spinal cord of injured and stroke subjects in order to generate or improve lost motor function. 

In functional electrical stimulation, the typical stimulation waveform is a train of rectangular pulses. This shape is used because of its effectiveness as well as relative ease of generation. All three parameters of a stimulation train, that is, frequency, amplitude, and pulse-width, have effect on muscle contraction. Generally, the stimulation frequency is kept as low as possible, to prevent muscle fatigue and to conserve stimulation energy. The determining factor is the muscle fusion frequency at which a smooth muscle response is obtained. This frequency varies however, it can be as low as 12-14 Hz and as high as 50 Hz. In most cases, the stimulation frequency is kept constant for a certain application. This is true both for surface as well as implanted electrodes. 

Slager, C.J., Schuurbiers, J.C.H., Oomen, J.A.F., Bom, N., 1993. Electrical nerve and muscle stimulation by radio frequency surgery role of direct current loops around the active electrode. IEEE Trans. Biomed. Eng. 40, 182-187. 

One electrotherapy modality is electrical stimulation (ES). This is a technique in which an electrical current pulse flows between an active (cathode) and indifferent (anode) electrode, causing depolarization of the cellular membranes and generation of action potentials in nerves and muscle contraction. 

The NMES device takes over the function of the brain and sends impulses to the electrodes, which are applied directly onto the muscle. It does not matter to the muscle whether the impulse comes from the brain or from an external device—the effect is the same. Neuromuscular electrical stimulation therapy is not dangerous for the human body because it works with low frequency, so the heart is not be exposed to any danger. The therapy can be applied on most parts of the body, but on some parts it is more difficult to build up the muscles. The only exception is the breast, because the therapy can have many influences on them. Further restrictions on use of the NMES device are if the patient has other internal electrical devices, for example, a pacemaker, or if the patient has established infections or wounds. 

Whilst testing and selecting the NMES device it was clear that the NMES device has to be able to transmit the electrical impulses to the textile electrodes so that the therapy can be as effective and comfortable as possible. The NMES therapy stimulates the muscles, which produces muscle growth. A balance had to be achieved so that on the one hand the electrodes can work as effectively as possible and on the other hand the treatment is as comfortable as possible for the patient. During the research three different NMES devices were tested the SaneoSport NMES device, the Beurer EM 41 NMES device and the Beurer EM 35 NMES device. Finally, the Beurer EM 35 device was applied in the medical back belt because it has the required feamres and got the best testing results. The NMES device Beurer EM 35 is shown in Fig. 6.5 [3]. 

The tests have shown that neuromuscular electrical stimulation has the opportunity to prickle the muscles so that they will not get weaker. The tests have shown that Shieldex silver-plated nylon 2-ply can be applied direcfly onto the skin. Usually electrodes are used in combination with liquid or gel to make them more conductive and to prevent any irritations or wounds. The applied textile electrodes were used without any liquid or gel and the tests have shown that the textile electrodes did not have any negative influences on the skin. The electrical impulse can easily be transmitted and electrodes have the possibility to prickle the muscles whilst conducting electricity. To conclude, a lumbar back belt was made with the function to stabilize the back and make straight posture possible, and the muscles in the back can be stimulated by the integrated neuromuscular electrical stimulation. 

Functional electrical stimulation (FES) of neural tissue provides a method to restore normal function to neurologically impaired individuals. By inserting electrode inside or near nerves, it is possible to activate pathways to the brain or to muscles. Functional nerve stimulation (FNS) is often used to describe applications of electrical stimulation in the peripheral nervous system. Neural prostheses refer to applications for which electrical stimulation is used to replace a function previously lost or damaged. 

Figure 1 Example of electrode placement for electrical stimulation of the quadriceps and hamstring muscles. Source From accelerated clinical practice, chronic obstructive pulmonary disease, www. acplus.com (45).

Hybrid thin-film polyimide electrodes integrated in silicone guidance channels have been fabricated as cuffs for electrical stimulation of peripheral nerves [58], Cuff electrodes wrap around a nerve trunk. They are used to record sensory signals from peripheral nerves or stimulate motor fibers to activate muscles [59]. 

The LCX is punctuated distal to the flow probe with a chrome-vanadium-steel electrode (3 mm length, 1 mm diameter). The electrode (anode) is placed in the vessel in contact with the intimal lining and connected over a Teflon coated wire to a 9 Volt battery, a potentiometer and an amperemeter. A disc electrode (cathode) is secured to a subcutaneous thoracal muscle layer to complete the electrical circuit. The intima is stimulated with 150 pA for 6 h. During this time, gradually an occluding thrombosis is formed. 

In recent years, ECT has been much improved. A muscle relaxant is given before treatment, which is done under brief anesthesia. Electrodes are placed at precise locations on the head to deliver electrical impulses. The stimulation causes a brief ( 30 seconds) seizure within the brain. The person receiving ECT does not consciously experience the electrical stimulus. For full therapeutic benefit, at least several sessions of ECT, typically given at the rate of three per week, are required. Electroconvulsive therapy appears to increase the sensitivity of postsynaptic 5-HT receptors and upregulation of 5-HTia postsynaptic receptors. 

Like the EEG, the EMG is a summation of cellular activity however, the EMG is primarily a result of the firing of muscle cells. If many muscle cells fire simultaneously (as happens when a muscle contracts), the electrical potentials generated near the surface of the skin will reflect that muscular activity. In practice, a very fine electrode is inserted into the muscle to stimulate a specific region. A second electrode or set of electrodes can then detect the resultant muscle activity. The EMG, then, is used primarily to detect abnormalities in muscle excitation. 

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