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  • Articles  (12)
  • Electrical stimulation  (12)
  • 2010-2014
  • 1990-1994  (6)
  • 1985-1989  (6)
  • 1950-1954
  • Technology  (12)
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  • Articles  (12)
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  • 1
    Electronic Resource
    Electronic Resource
    Role of the tendon in the dynamic performance of three different load-moving muscles (1994)
    Springer
    Annals of biomedical engineering 22 (1994), S. 682-691 
    Details
    ISSN: 1573-9686
    Keywords: Tendon ; Muscle ; Model ; Electrical stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The effect of the tendon's viscoelastic properties on the dynamic performance of three different load-moving muscles was determined. The frequency response models of the cat's medial gastrocnemius (MG), extensor digitorum longus (EDL), and tibialis anterior (TA) with and without their tendons were derived under sinusoidal shortening-lengthening, manipulated by orderly recruitment and derecruitment of motor units together with firing rate increase and decrease. The passive load sizes applied to the muscles were approximately 30%–40% of each muscle's maximal isometric force. It was shown that the tendon has a moderate effect on the dynamic response of muscles while moving loads of fixed mass. The MG and EDL without their tendons show a decrease in high frequency gain (2–5 dB) and increasing phase lag angles (7°–9°). In contrast, the TA without its tendon shows an increase in high frequency gain (2 dB) and decreasing phase lag angles (20°) compared with the same muscle with the tendon. It was concluded that tendon's viscoelastic properties have a moderate effect during load-moving contractions, influencing the dynamic performance of different muscles in a different manner.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02368293
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  • 2
    Electronic Resource
    Electronic Resource
    Attenuation of pathological tremors by functional electrical stimulation I: Method (1992)
    Springer
    Annals of biomedical engineering 20 (1992), S. 205-224 
    Details
    ISSN: 1573-9686
    Keywords: Tremor ; Electrical stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract In this study we explored the possibility of suppressing pathological tremors using closed-loop functional electrical stimulation (FES) to activate the tremorogenic muscles out-of-phase. A displacement signal monitored with a transducer was filtered so as to be “tuned” to the tremor frequency at the wrist or elbow. The filtered signal was used to amplitude-modulate the electrical stimulation. The design process was based on measurements of the open-loop frequency response characteristics of the forearm and hand to stimulation of the elbow and wrist flexors and extensors in a number of subjects. These data allowed us to identify closed-loop configurations, which attenuated 2–5 Hz tremors substantially, while only minimally attenuating functional movements in the 0–1 Hz range. There was a fairly delicate balance between efficacy and the risk of instability. However, designs were identified that offered enough tremor suppression and adequate immunity to muscle/load variations for the technique to be considered seriously for clinical application.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02368521
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  • 3
    Electronic Resource
    Electronic Resource
    Comparison of three methods of electrical stimulation for converting skeletal muscle to a fatigue resistant power source suitable for cardiac assistance (1990)
    Springer
    Annals of biomedical engineering 18 (1990), S. 239-250 
    Details
    ISSN: 1573-9686
    Keywords: Electrical stimulation ; Skeletal muscle ; Cardiac assistance ; Muscle fatigue ; Skeletal muscle ventricle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Twelve dogs were sorted into 3 equal groups, and thein-situ right latissimus dorsi muscle of each dog was stimulated via its motor nerve for a period of 6 weeks. The resulting isotonic contractions were used to pump fluid in an implanted, 2-chambered, compressible pouch system. Three methods of electrical stimulation were used: (a) continuous 2 sec−1 single pulses that caused muscle twitching, (b) a 250 msec train of pulses (36 sec−1) that caused tetanic muscle contractions and was repeated every 2 sec for 15 min followed by a 15 min period of rest, and (c) alternating 15 min periods of the above 2 stimulation methods to cause alternating twitch and tetanic contractions. The 2 sec−1 twitch stimulation and the combined twitch/tetanic stimulation methods resulted in a 100% conversion to fatigue-resistant fibers within 6 weeks. Standardized muscle function tests were performed weekly. With the twitch stimulation (Method 1), the time to fatigue increased from 9 to 116 min (p〈0.001), but fluid pumping ability of the muscle decreased substantially from 0.25 to 0.14 liters min−1 (p〈0.05). With the intermittent tetanic stimulation (Method 2), the fatigue resistance increased only slightly from 7 to 11 minutes (p=NS), and pumping ability was unchanged. With the combined (twitch-tetanic) stimulation (Method 3), the time to fatigue increased from 9 to 107 min (p〈0.001), and the pumping ability did not significantly change from 0.20 to 0.22 liters min−1 (p=NS). These results suggest that a combined electrical stimulation method which produces both twitches and tetanic contractions can achieve rapid fiber conversion and increased fatigue resistance without loss of muscle strength.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02368440
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  • 4
    Electronic Resource
    Electronic Resource
    Optimization of pulse train duration for the electrical stimulation of a skeletal muscle ventricle in the dog (1990)
    Springer
    Annals of biomedical engineering 18 (1990), S. 467-478 
    Details
    ISSN: 1573-9686
    Keywords: Skeletal muscle ventricle ; Electrical stimulation ; Cardiac assistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The optimal means of electrically stimulating a skeletal muscle to contract around a fluid-filled pouch (i.e., a skeletal muscle ventricle [SMV]) has not been determined. A SMV was made from the latissimus dorsi muscle in five dogs and the rectus abdominis muscle in five dogs, and each SMV was electrically stimulated via the motor nerve(s) to contract around a fluid-filled pouch, which was connected to a mock circulatory system. The pulse train duration (PTD) was varied from 100 ms to 800 ms in 100 ms increments to determine the effect of this variable upon SMV output. The pulse width of the electrical stimulus was kept constant at 100 μs and the pulse frequency was maintained at 50s−1. For SMV contraction rates of 20, 30, and 40 min−1, the optimal PTD was 400 ms for both muscles. The peak output was 710 ml min−1 for the rectus SMV and 556 ml min−1 for the latissimus SMV. For an SMV contraction rate of 10min−1, the optimal PTD was 800 ms for the rectus SMV and 600 ms for the latissimus SMV. Use of less than an optimal PTD caused reductions in SMV output of 25–50%. Although SMVs made from rectus abdominis and latissimus dorsi had similar values for the optimal PTD, the maximum SMV output was usually greater with the rectus abdominis in this acute study with untrained muscles. We conclude that PTD is an important variable to control, which can markedly affect results when studying the potential use of skeletal muscle power for cardiac assistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02364611
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  • 5
    Electronic Resource
    Electronic Resource
    Regulating knee joint position by combining electrical stimulation with a controllable friction brake (1990)
    Springer
    Annals of biomedical engineering 18 (1990), S. 575-596 
    Details
    ISSN: 1573-9686
    Keywords: Electrical stimulation ; Muscle ; Spinal cord injury ; Control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Hybrid FES gait restoration systems which combine stimulation with controllable mechanical damping elements at the joints show promise for providing good control of limb motion despite variations in muscle properties. In this paper we compared three controllers for position tracking of the free swinging shank in able-bodied subjects. The controllers were open-loop (OL), proportional-derivative closed-loop (PD), and bang-bang plus controlled-brake control (CB). Both OL and PD controllers contained a forward path element, which inverted a model of the electrically stimulated muscle and limb system. The CB control was achieved by maximally activating the appropriate muscle group and controlling the brake to be a “moving-wall” against which the limb pushed. The CB control resulted in superior tracking performance for a wide range of position tracking tasks and muscle fatigue states but required no calibration or knowledge of muscle properties. The disadvantages of CB control include excess mechanical power dissipation in the brake and impact forces applied to the skeletal system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02368449
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  • 6
    Electronic Resource
    Electronic Resource
    Imbalanced biphasic electrical stimulation: Muscle tissue damage (1990)
    Springer
    Annals of biomedical engineering 18 (1990), S. 407-425 
    Details
    ISSN: 1573-9686
    Keywords: Electrical stimulation ; Tissue damage ; Electrode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The effects of imbalanced biphasic stimulation were studied on cat skeletal muscle to determine if greater charge densities can be safely used than with balanced or monophasic stimulation. The results of the study indicate that imbalanced biphasic stimulation can be tolerated safely by tissue at or below a net dc current density of 35 μA/mm2 and not safely tolerated at or above a net dc current of 50 μA/mm2. Monophasic stimulation has been shown to be safe at or below net dc current levels of 10 μA/mm2 and in these studies we found it was not safe at or above net dc current levels of 20 μA/mm2. Stimuli were applied to muscles via coiled wire intramuscular electrodes using a regulated current source. Since the safe average current density was higher for imbalanced biphasic stimulation than for monophasic stimulation, this suggests that: (a) pH change is not the primary reaction causing tissue damage and (b) the damaging electrochemical process that takes place during a cathodic stimulation pulse can be reversed by an anodic pulse having substantially less charge than its companion cathodic pulse. We conclude that greater cathodic charge densities can be safely employed with imbalanced biphasic stimulation than with either monophasic stimulation or balanced charge biphasic stimulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02364157
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  • 7
    Electronic Resource
    Electronic Resource
    Histologic and physiologic evaluation of electrically stimulated peripheral nerve: Considerations for the selection of parameters (1989)
    Springer
    Annals of biomedical engineering 17 (1989), S. 39-60 
    Details
    ISSN: 1573-9686
    Keywords: Electrical stimulation ; Neural damage ; Peripheral nerve electrode ; Peroneal nerve ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Helical electrodes were implanted around the left and right common peroneal nerves of cats. Three weeks after implantation one nerve was stimulated for 4–16 hours using charge-balanced, biphasic, constant current pulses. Compound action potentials (CAP) evoked by the stimulus were recorded from over the cauda equina before, during and after the stimulation. Light and electron microscopy evaluations were conducted at various times following the stimulation. The mere presence of the electrode invariably resulted in thickened epineurium and in some cases increased peripheral endoneurial connective tissue beneath the electrodes. Physiologic changes during stimulation included elevation of the electrical threshold of the large axons in the nerve. This was reversed within one week after stimulation at a frequency of 20 Hz, but often was not reversed following stimulation at 50–100 Hz. Continuous stimulation at 50 Hz for 8–16 hours at 400 μA or more resulted in neural damage characterized by endoneurial edema beginning within 48 hours after stimulation, and early axonal degeneration (EAD) of the large myelinated fibers, beginning by 1 week after stimulation. Neural damage due to electrical stimulation was decreased or abolished by reduction of the duration of stimulation, by stimulating at 20 Hz (vs. 50 Hz) or by use of an intermittent duty cycle. These results demonstrate that axons in peripheral nerves can be irreversely damaged by 8–16 hours of continuous stimulation at 50 Hz. However, the extent to which these axons may subsequently regenerate is uncertain. Therefore, protocols for functional electrical stimulation in human patients probably should be evaluated individually in animal studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02364272
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  • 8
    Electronic Resource
    Electronic Resource
    Comparison of neural damage induced by electrical stimulation with faradaic and capacitor electrodes (1988)
    Springer
    Annals of biomedical engineering 16 (1988), S. 463-481 
    Details
    ISSN: 1573-9686
    Keywords: Electrical stimulation ; Neural damage ; Capacitor electrode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Arrays of platinum (faradaic) and anodized, sintered tantalum pentoxide (capacitor) electrodes were implanted bilaterally in the subdural space of the parietal cortex of the cat. Two weeks after implantation both types of electrodes were pulsed for seven hours with identical waveforms consisting of controlled-current, chargebalanced, symmetric, anodic-first pulse pairs, 400 μsec/phase and a charge density of 80–100 μC/cm2 (microcoulombs per square cm) at 50 pps (pulses per second). One group of animals was sacrificed immediately following stimulation and a second smaller group one week after stimulation. Tissues beneath both types of pulsed electrodes were damaged, but the difference in damage for the two electrode types was not statistically significant. Tissue beneath unpulsed electrodes was normal. At the ultrastructural level, in animals killed immediately after stimulation, shrunken and hyperchromic neurons were intermixed with neurons showing early intracellular edema. Glial cells appeared essentially normal. In animals killed one week after stimulation most of the damaged neurons had recovered, but the presence of shrunken, vacuolated and degenerating neurons showed that some of the cells were damaged irreversibly. It is concluded that most of the neural damage from stimulations of the brain surface at the level used in this study derives from processes associated with passage of the stimulus current through tissue, such as neuronal hyperactivity rather than electrochemical reactions associated with current injection across the electrode-tissue interface, since such reactions occur only with the faradaic electrodes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02368010
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  • 9
    Electronic Resource
    Electronic Resource
    Characterization and control of muscle response to electrical stimulation (1987)
    Springer
    Annals of biomedical engineering 15 (1987), S. 485-501 
    Details
    ISSN: 1573-9686
    Keywords: Muscle ; Electrical stimulation ; Control theory ; Spinal cord injury
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The maintenance of upright posture in neurologically intact human subjects is mediated by two major nervous pathways. The first, leading from the cerebral cortex through the spinal cord to motor neurons, activates muscles which produce postural movements. The second, leading from various sensory organs to higher centers, provides sensory feedback regarding the postural state. The path through the spinal cord is no longer intact in victims of spinal cord injury and loss of normal control of muscle activity results. Functional neuromuscular stimulation (FNS) has been shown as a feasible method for obtaining muscle contraction in paraplegic and has been proposed as a means for control of antero-posterior sway to make upright posture possible for these individuals. Before muscle can be controlled through the use of FNS, the response of muscle to electrical stimulation must be understood. In past studies, linear control theory has been applied to the analysis of this response and to the testing of various controllers. The aim of this study was to demonstrate some control issues in FNS using linear control theory, as it applies to electrical stimulation of muscle for stabilization of posture. The linearity of the muscle response was improved through closed-loop control using pole compensation techniques. The excess phase shift of the system due to the time delay in the muscle response, however, limits the ability to increase the open-loop gain in order to obtain improved performance. A suggestion for further study is the application of this methodology for uses in posture control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02363567
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  • 10
    Electronic Resource
    Electronic Resource
    Recruitment properties of monopolar and bipolar epimysial electrodes (1986)
    Springer
    Annals of biomedical engineering 14 (1986), S. 53-66 
    Details
    ISSN: 1573-9686
    Keywords: Neural prostheses ; Motor prosthesis ; Electrode ; Electrical stimulation ; Muscle stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Muscle force was studied as a function of stimulus parameters, epimysial electrode position relative to nerve supply, and muscle length to provide insight into the properties of motor prostheses that employ epimysial electrodes. The results of the acute experiments indicated that the dependence of recruitment (force versus stimulus amplitude) on muscle length was minimal for a monopolar electrode positioned close to nerve entrance or 5 mm proximal to the motor point. The selectivity of stimulation (minimal activation of adjacent muscles) was best, and the recruitment rate the highest, for an electrode placed close to the nerve entrance. A bipolar pair of electrodes placed on the superficial surface of the muscle opposite to the nerve entrance gave better selectivity than the monopolar electrode at the low end of the recruitment range, and poorer selectivity at the high end. This electrode configuration required greater stimulus currents and exhibited a lower recruitment gain than was obtained for a monopolar electrode in the same position. Examination of tissue surrounding the electrode 30 days after implantation showed that the fibrous tissue encapsulating the electrode had been incorporated into the fascial layer. Slightly larger dependence on muscle length and lower selectivity of stimulation were measured after encapsulation than were measured in the acute experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02364648
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  • 11
    Electronic Resource
    Electronic Resource
    Effects of waveform parameters on comfort during transcutaneous neuromuscular electrical stimulation (1985)
    Springer
    Annals of biomedical engineering 13 (1985), S. 59-74 
    Details
    ISSN: 1573-9686
    Keywords: Electrical stimulation ; Comfort ; Parameters ; Waveforms ; Pulse duration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Twenty-three females between the ages of 19 and 35 were studied in order to compare the effects of variations in pulse duration, waveform symmetry, and source regulation on comfort during quadriceps surface stimulation at amplitudes necessary to produce 27 Nm torque. Stimulation parameters compared were: 1) 50 and 300 μs pulse durations, 2) asymmetrical and symmetrical biphasic waveforms, and 3) current and voltage source regulation. Subjects overwhelmingly preferred the 300 μs pulse duration regardless of waveform or source regulation, strongly preferred the symmetrical biphasic waveform, and had inconsistent preference for either regulated voltage or regulated current sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02371250
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  • 12
    Electronic Resource
    Electronic Resource
    Acute and chronic implantation of coiled wire intraneural electrodes during cyclical electrical stimulation (1985)
    Springer
    Annals of biomedical engineering 13 (1985), S. 75-93 
    Details
    ISSN: 1573-9686
    Keywords: Electrodes ; Implantable electrodes ; Nerve electrodes ; Peripheral nerve electrodes ; Electrical stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The posterior tibial nerves of 18 rabbits were intraneurally implanted with coiled wire electrodes for up to 9 weeks to evaluate their usefulness for neuromuscular electrical stimulation. In one group an electrode was implanted and removed in one leg while the other leg was chronically implanted. A second group was chronically implanted without electrical stimulation in one leg and implanted with cyclical electrical stimulation applied through the electrode in the other leg. No significant changes in nerve conduction velocities between the time of implantation and up to 9 weeks post-implantation were observed in either the stimulated or the non-stimulated nerves. Little change in motor current threshold was observed beyond 10 days postimplantation. The nerves showed little or no histologic demyelination or denervation in most specimens, although in about 40% of the nerves, a bulbous formation of connective tissue was observed at electrode entry and exit sites with some demyelination in these regions. The spinal cords showed no histologic abnormalities in either group. The gastrocenemius and soleus muscles showed only occasional signs of denervation. One cat was implanted in both the posterior tibial and peroneal nerves of each leg for a 4-year period. Threshold current showed very little change during the implantation period. The nerves showed minimal focal demyelination at the electrode site and the muscles showed normal fibers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02371251
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