Electro-stimulating implants for bone regeneration: parameter analysis and design optimization

This thesis investigated a bipolar induction screw system with an integrated coil for bone electrical stimulation. The aim was to analyse the influence of the stimulation parameters and electro-stimulating implants parameters on bone regeneration and carry out a parameter optimization for bone electrical stimulation. Finite element analysis was used to calculate the electric field distributions in the bone. The results showed that the screw’s z-direction positioning (moving in and out of femoral head) yields the highest effect on the volume tissue activated in patient’s femoral head model

Improved Functional Electrical Stimulation (FES) systems for optimized selectivity

En el presente trabajo de Tesis se aborda el tema de selectividad en la activación muscular en las aplicaciones de estimulación eléctrica funcional en el miembro superior. Este tipo de tecnología presenta una serie de problemas, de los cuales se destaca la dificultad de estimular solo un musculo debido al reducido tamaño de ellos y la alta densidad de músculos presentes. El problema este, llamado “oveflow" en inglés, aparece debido a la dificultad de controlar el camino de la corriente eléctrica debajo de la piel hacia el musculo. Los electrodos tipo matriz han sido la apuesta de varios estudios para afrontar estas dificultades y varias soluciones se han presentado los últimos 10 años. Estos estudios se enfocan en el desarrollo de sistemas y de la tecnología electrónica necesaria. Sin embargo, faltan estudios de los parámetros que influyen en la activación selectiva de los músculos y como optimizar todos estos parámetros. El objetivo de esta tesis es el desarrollo de un sistema de estimulación eléctrica funcional superficial, basado en los electrodos tipo matriz, que optimiza la selectividad muscular. Se conoce desde la bibliografía que el camino de la corriente eléctrica debajo de la piel depende de una serie de factores. Entre ellos se encuentran la posición, la forma y el tamaño del electrodo de cátodo, la posición del electrodo de ánodo y la impedancia de la membrana de gel del electrodo. Esta tesis se enfoca en optimizar estos factores que permiten modular el campo eléctrico que se genera debajo del electrodo. El sistema que se ha desarrollado se usó con ese objetivo. El sistema se ha evaluado en dos escenarios: en pacientes con temblor y pacientes con lesión medular

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 218, April 1981

This bibliography lists 161 reports, articles, and other documents introduced into the NASA scientific and technical information system in March 1981

Aerospace Medicine and Biology. A continuing bibliography with indexes

This bibliography lists 244 reports, articles, and other documents introduced into the NASA scientific and technical information system in February 1981. Aerospace medicine and aerobiology topics are included. Listings for physiological factors, astronaut performance, control theory, artificial intelligence, and cybernetics are included

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 165, March 1977

This bibliography lists 198 reports, articles, and other documents introduced into the NASA scientific and technical information system in February 1977

ElectroCutscenes: Realistic Haptic Feedback in Cutscenes of Virtual Reality Games Using Electric Muscle Stimulation

Cutscenes in Virtual Reality (VR) games enhance story telling by delivering output in the form of visual, auditory, or haptic feedback (e.g., using vibrating handheld controllers). Since they lack interaction in the form of user input, cutscenes would significantly benefit from improved feedback. We introduce the concept and implementation of ElectroCutscenes, a concept in which Electric Muscle Stimulation (EMS) is leveraged to elicit physical user movements to correspond to those of personal avatars in cutscenes of VR games while the user stays passive. Through a user study (N=22) in which users passively received kinesthetic feedback resulting in involuntarily movements, we show that ElectroCutscenes significantly increases perceived presence and realism compared to controller-based vibrotactile and no haptic feedback. Furthermore, we found preliminary evidence that combining visual and EMS feedback can evoke movements that are not actuated by either of them alone. We discuss how to enhance realism and presence of cutscenes in VR games even when EMS can partially rather than completely actuate the desired body movements

Stimulation discomfort comparison of asynchronous and synchronous methods with multi-field electrodes

Functional Electrical Stimulation (FES) is a technique that consists on applying electrical current pulses to artificially activate motor nerve fibers and produce muscle contractions to achieve functional movements. The main applications of FES are within the rehabilitation field, in which this technique is used to aid recovery or to restore lost motor functions. People that benefit of FES are usually patients with neurological disorders which result in motor dysfunctions; most common patients include stroke and spinal cord injury (SCI). Neuroprosthesis are devices that have their basis in FES technique, and their aim is to bridge interrupted or damaged neural paths between the brain and upper or lower limbs. One of the aims of neuroprosthesis is to artificially generate muscle contractions that produce functional movements, and therefore, assist impaired people by making them able to perform activities of daily living (ADL). FES applies current pulses and stimulates nerve fibers by means of electrodes, which can be either implanted or surface electrodes. Both of them have advantages and disadvantages. Implanted electrodes need open surgery to place them next to the nerve root, so these electrodes carry many disadvantages that are produced by the use of invasive techniques. In return, as the electrodes are attached to the nerve, they make it easier to achieve selective functional movements. On the contrary, surface electrodes are not invasive and are easily attached or detached on the skin. Main disadvantages of surface electrodes are the difficulty of selectively stimulating nerve fibers and uncomfortable feeling perceived by users due to sensory nerves located in the skin. Electrical stimulation surface electrode technology has improved significantly through the years and recently, multi-field electrodes have been suggested. This multi-field or matrix electrode approach brings many advantages to FES; among them it is the possibility of easily applying different stimulation methods and techniques. The main goal of this thesis is therefore, to test two stimulation methods, which are asynchronous and synchronous stimulation, in the upper limb with multi-field electrodes. To this end, a purpose-built wrist torque measuring system and a graphic user interface were developed to measure wrist torque produced with each of the methods and to efficiently carry out the experiments. Then, both methods were tested on 15 healthy subjects and sensitivity results were analyzed for different cases. Results show that there are significant differences between methods regarding sensation in some cases, which can affect effectiveness or success of FES.Tecnalia and Fundación Iñaki Goenag

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 127, April 1974

This special bibliography lists 279 reports, articles, and other documents introduced into the NASA scientific and technical information system in March 1974