Biomedical subjects

A Cliquet Júnior

Publications and source records attributed to A Cliquet Júnior.

5 recordsLinked to original sources

PubMed2000

An artificial grasping evaluation system for the paralysed hand.

Neuromuscular electrical stimulation (NMES) has been used in upper limb rehabilitation towards restoring motor hand function. Quantitative evaluation of the artificially generated movement is necessary to achieve proper muscle activation. Custom-made gloves instrumented with force and position transducers were used to evaluate artificial quadriplegic grasping for a drinking activity. In spite of different sensor position, stimulation parameter dependence and lack of repeatability, grasp patterns achieved with the application of NMES follow the same patterns previously obtained with normal subjects, regarding force distribution among fingers and the shape of force curves. Larger forces were exerted by the thumb (average ranged from 2.8 to 4.5 N) following by index or long finger (average ranged from 1.8 to 3 N). The forces exerted ranged within the same interval as those previously measured and were sufficient to grasp an object of 10 N. Finger position achieved by interphalangeal joint status indicated the opening size of the hand throughout the range of movement. The instrumented gloves offer an alternative force and position feedback system for use in cylindrical grasp evaluation. The gloves can be used in a closed-loop control system, allowing on-line adjustment or in a clinical application to evaluate the results of a rehabilitation programme.

Biofeedback, Psychology↗

PubMed1995

A feasibility study on a new artificial sphincter for colostomy.

Although many efforts have been put forth, fecal incontinence of colostomates is still an unsolved problem. Among the techniques available to improve continence, the use of electromagnetic/mechanical power has not been explored. Our work looks at the characteristics needed by the components of an artificial sphincter where the power of sphincteric muscles is substituted with electromagnetic/mechanical power, and the mechanical absence of muscles is replaced by a plastic band. Experimental work was done with isolated colon of 26 mongrel dogs, and all of them became continent by an intraluminal gas pressure over 80 mm Hg when a final perimeter between 3.7 and 4.7 cm was reached. No macroscopic lesions were noted on the guts' surface beneath the plastic band. The largest band displacement was 4.2 cm, and the traction force was under 50 N.

Animals↗

PubMed1995

Electrotactile stimulator for artificial proprioception.

With the goal of investigating artificial proprioception elicited by electrical stimulation, we have developed a tactile phi phenomenon-based stimulator. This two-channel microprocessed pulse amplitude modulation system generates two different envelope waveforms (triangular and elliptical) and allows programming and visualizing of its main parameters: pulse with (0.1-10 ms), pulse frequency (0.1-10 kHz), modulation frequency (0.3-10 Hz), current intensity (up to 20 mA), and the amplitude modulation index (0-100%). In vivo experiments with 5 normal persons have shown that it is possible to elicit a moving fused phantom image with good resolution. A triangular envelope is good for straight line sensations while the elliptical one is more comfortable and has better resolution for all kinds of moving images.

Biofeedback, Psychology↗

PubMed1995

An artificial neural system for closed loop control of locomotion produced via neuromuscular electrical stimulation.

The use of neuromuscular electrical stimulation for restoration of gait in spinal cord injured subjects has been seriously pursued by many investigators for the past 15 years. By and large, however, systems to date require the intervention of a person, be it the patient or an observer, and are restricted to control of stimulation onset and termination. Further, existing systems are not adaptable to environmental and patient variations. This work proposes a system that relies on neural computing to determine proper muscle activation patterns from biomechanical signals. The intelligent system is trained to perform gait under supervision, after which it can be used to control muscle stimulation in an unknown environment. Computer simulations suggest that the best neural architecture for control of gait is a neural network including units corresponding to movement history. Separate networks for the stance and swing phases, respectively, were found to work better than a single neural network trained on the entire gait cycle. The artificial neural device proposed here also includes a voice recognition system that will allow for voluntary locomotion. A safety circuit has been designed to preclude acceptance of unwanted vocal commands in the latter system.

Computer Simulation↗

PubMed1995

A paradigm for design of closed loop neuromuscular electrical stimulator control systems.

The use of neuromuscular electrical stimulation (NMES) for rehabilitation of gait in spinal patients is widely known. The best results can be obtained with the use of biomechanical sensors and a closed loop NMES system. One of the biggest problems faced in the design of control systems for closed-loop operation, in gait rehabilitation, is the variation of the mechanical conditions during the phases of gait. This work presents a new approach to ease the design of rule-based closed loop systems for operation in conditions such as gait rehabilitation.

Electric Stimulation↗