Evaluation of motor neuron excitability by CMAP scanning with modulated current

It is important to have better evaluation and understanding of the motor neuron physiology, with the goal to early and objectively diagnose and treat patients with neurodegenerative pathologies. The Compound Muscle Action Potential (CMAP) scan is a non-invasive diagnosis technique for neurodegenerative pathologies, such as ALS, and enables a quick analysis of the muscle action potentials in response to motor nerve stimulation. This work aims to study the influence of different pulse modulated waveforms in peripheral nerve excitability by CMAP scan technique on healthy subjects. A total of 13 healthy subjects were submitted to the same test. The stimuli were applied in the medium nerve on the right wrist and electromyography signal collected on the Abductor Pollicis Brevis (APB) muscle surface on the right thumb. Stimulation was performed with an increasing intensities range from 4 to 30 mA, with varying steps, 3 stimuli per step. The procedure was repeated 4 times per subject, each repetition using a different single pulse stimulation waveform: monophasic square, monophasic triangular, monophasic quadratic and biphasic square. Results were retrieved from the averaging of the stimuli on each current intensity step. The square pulse needs less current intensity to generate the same response amplitude regarding the other waves and presents a more steep curve slope and this effect is gradually decreasing for the triangular and quadratic pulse,respectively, being the difference even more evident regarding the biphasic pulse. The control of the waveform stimulation pulse allows varying the stimulusresponse curve slope

Pain as Feedback for Bionic Limbs

Abstract: This paper looks at advancements made in the area of thought controlled mechanical prosthesis that are being developed for amputees in order for them to regain mobility. It focuses on the brain-machine interface which is hardware and software that is used to control mechanical prosthesis or bionic limbs by sending and receiving signals between the prosthetic and the users mind. There is signaling feedback from the prosthesis to the user that indicates how much pressure is being applied to an object that is being grasped for instance. This paper explores the notion of the value of pain as a warning in the form of artificial feedback to help prevent damage and death to people and posits that pain should be included in the feedback loop so that when, for example, an artificial hand is in imminent danger of being burned the wearer is alerted

Wireless Power Transfer Techniques for Implantable Medical Devices:A Review

Wireless power transfer (WPT) systems have become increasingly suitable solutions for the electrical powering of advanced multifunctional micro-electronic devices such as those found in current biomedical implants. The design and implementation of high power transfer efficiency WPT systems are, however, challenging. The size of the WPT system, the separation distance between the outside environment and location of the implanted medical device inside the body, the operating frequency and tissue safety due to power dissipation are key parameters to consider in the design of WPT systems. This article provides a systematic review of the wide range of WPT systems that have been investigated over the last two decades to improve overall system performance. The various strategies implemented to transfer wireless power in implantable medical devices (IMDs) were reviewed, which includes capacitive coupling, inductive coupling, magnetic resonance coupling and, more recently, acoustic and optical powering methods. The strengths and limitations of all these techniques are benchmarked against each other and particular emphasis is placed on comparing the implanted receiver size, the WPT distance, power transfer efficiency and tissue safety presented by the resulting systems. Necessary improvements and trends of each WPT techniques are also indicated per specific IMD

Modulation of electrical stimulation applied to human physiology and clinical diagnostic

The use, manipulation and application of electrical currents, as a controlled interference mechanism in the human body system, is currently a strong source of motivation to researchers in areas such as clinical, sports, neuroscience, amongst others. In electrical stimulation (ES), the current applied to tissue is traditionally controlled concerning stimulation amplitude, frequency and pulse-width. The main drawbacks of the transcutaneous ES are the rapid fatigue induction and the high discomfort induced by the non-selective activation of nervous fibers. There are, however, electrophysiological parameters whose response, like the response to different stimulation waveforms, polarity or a personalized charge control, is still unknown. The study of the following questions is of great importance: What is the physiological effect of the electric pulse parametrization concerning charge, waveform and polarity? Does the effect change with the clinical condition of the subjects? The parametrization influence on muscle recruitment can retard fatigue onset? Can parametrization enable fiber selectivity, optimizing the motor fibers recruitment rather than the nervous fibers, reducing contraction discomfort? Current hardware solutions lack flexibility at the level of stimulation control and physiological response assessment. To answer these questions, a miniaturized, portable and wireless controlled device with ES functions and full integration with a generic biosignals acquisition platform has been created. Hardware was also developed to provide complete freedom for controlling the applied current with respect to the waveform, polarity, frequency, amplitude, pulse-width and duration. The impact of the methodologies developed is successfully applied and evaluated in the contexts of fundamental electrophysiology, psycho-motor rehabilitation and neuromuscular disorders diagnosis. This PhD project was carried out in the Physics Department of Faculty of Sciences and Technology (FCT-UNL), in straight collaboration with PLUX - Wireless Biosignals S.A. company and co-funded by the Foundation for Science and Technology.Fundação para a Ciência e Tecnologia (FCT); PLUX - Wireless Biosignals, S.A.; FCT-UNL- CEFITE

Bidirectional Propulsion of Devices Along the Gastrointestinal Tract Using Electrostimulation

This thesis describes a method for propelling devices such as video capsule endoscopes in either direction along the small intestines using electrostimulation-induced muscular contractions. When swallowed, passive diagnostic ‘one-shot’ devices rely on sporadic peristaltic movement, possibly missing vital ‘areas of interest’. This bidirectional propulsion method provides active control for that all-important ‘second look’. Design considerations, within the dimensional constraints, required a device shape that would achieve maximum propulsion from safely induced useful contractions produced by the electrodes and encapsulated miniature electrostimulator. Construction materials would have to produce minimal friction against the mucosal surface while having the physical properties to facilitate construction and electrode attachment. Design investigations included coefficient of friction measurements of different construction materials and the evaluation of different capsule and electrode dimensions over a range of stimulation parameters, to obtain optimal propulsion. A swallowable 11 mm diameter device was propelled at 121 mm/min with stimulation parameters of 12.5 Hz, 20 ms, at 20 V in an anaesthetised pig. A modified passive video capsule endoscope was propelled at 120 mm/min with stimulation parameters of 12.5 Hz, 20 ms, at 10 V in an unanaesthetised human volunteer. A radio-controlled capsule incorporating an electrostimulator, voltage converter and 3 V power supply was propelled at 60 mm/min with stimulation parameters of 12.5 Hz, 20 ms, and 30 V in an anaesthetised pig. 4 Other possible uses of electrostimulation were investigated including propulsion of anally administered large intestine devices and introduction of the intestinal mucosal surface into a biopsy chamber. Results are presented. The ultimate aim of the project was to provide bidirectional propulsion for wireless remote controlled devices along the gastrointestinal tract utilising contractile force produced by electrostimulation of the intestinal wall. The controllability of this system could provide clinicians with a real time view of the entire small intestines without surgical enteroscopy