A compact-sized surface EMG sensor for myoelectric hand prosthesis

Myoelectric prosthesis requires a sensor that can reliably capture surface electromyography (sEMG) signal from amputees for its controlled operation. The main problems with the presently available EMG devices are their extremely high cost, large response time, noise susceptibility, less amplitude sensitivity, and larger size. This paper proposes a compact and affordable EMG sensor for the prosthetic application. The sensor consists of an electrode interface, signal conditioning unit, and power supply unit all encased in a single package. The performance of dry electrodes employed in the skin interface was compared with the conventional Ag/AgCl electrodes, and the results were found satisfactory. The envelope detection technique in the sensor based on the tuned RC parameters enables the generation of smooth, faster, and repeatable EMG envelope irrespective of signal strength and subject variability. The output performance of the developed sensor was compared with commercial EMG sensor regarding signal-to-noise ratio, sensitivity, and response time. To perform this, EMG data with both devices were recorded for 10 subjects (3 amputees and 7 healthy subjects). The results showed 1.4 times greater SNR values and 45% higher sensitivity of the developed sensor than the commercial EMG sensor. Also, the proposed sensor was 57% faster than the commercial sensor in producing the output response. The sEMG sensor was further tested on amputees to control the operation of a self-designed 3D printed prosthetic hand. With proportional control scheme, the myoelectric hand setup was able to provide quicker and delicate grasping of objects as per the strength of the EMG signal.

Prototipo de una Prótesis Mioeléctrica para la Emulación de una Articulación de Codo / Prototype of a Myoelectric Prosthesis for the Emulation of an Elbow Joint

En este trabajo se describe el desarrollo de un prototipo de prótesis mioeléctrica para la articulación de codo. Se dividió en tres partes, en la primera se describe el acondicionamiento de la señal mioeléctrica (SME) donde se propuso un circuito que está formado por una etapa de pre-amplificación, seguida de una etapa de filtrado, otra etapa de amplificación y por último la etapa de rectificación. Este circuito cumple con las especificaciones para la detección de la SME según el estado del arte. En la segunda parte se describe el procesamiento de la SME basado en el método TKEO, este se implementó en MatLAB (MathWorks- Natick, Massachusetts, USA) con la finalidad de detectar la actividad muscular, y resultó robusto y eficiente. La tercera parte se enfoca al diseño y construcción del prototipo, para el sistema de transmisión se usó un par de engranes y para el sistema de actuación los actuadores eléctricos; ambos se definieron según los criterios que se describen en este trabajo. Finalmente, se integraron las tres partes para la emulación de los movimientos flexión y extension del prototipo, haciendo uso del microprocesador (Arduino UNO) y del módulo de control de motores (Controlador de servo 1350 de Pololu).

In this paper the development of a prototype for a myoelectric prosthesis elbow joint is described. It is divided into three parts; the first is the conditioning of the myoelectric signal (SME) which proposed a circuit that is formed by a stage of pre-amplification, followed by a stage of filtering, another stage of amplification and finally a stage of rectification. This circuit complies with the specifications for the detection of the SME according to the state of the art. The second part is the processing of the SME based on the method TKEO, this was implemented in MatLAB (MathWorks - Natick, Massachusetts, USA) in order to detect if the muscle is active or not, and proved to be robust and efficient. The third part focuses on the design and realization of the prototype, in the system of transmission was used a couple of gears and for the system of actuation were electrical actuators; both were defined considering several criteria referred to in this work. Finally, the three parts were joined for the emulation of flexion and extension movements of the prototype, using the microprocessor (Arduino UNO) and control module (controller servo Pololu 1350).

Myoelectric Prostheses : Current Status and Problems to be Solved, a Rehabilitation Strategy for Higher Level Amputation Patients, and the Future Outlook / The Japanese Journal of Rehabilitation Medicine

Rehabilitation using myoelectric prosthesis for trans-radial amputees has become wide spread and well established in several developed countries. However, the clinical use of myoelectric prostheses for trans-radial amputees has not yet spread in Japan. It is well known that once amputees become accustomed to using their prosthesis efficiently through adequate rehabilitation, that various activities which the amputees had given up so far will become possible through enhanced bimanual activities. Although myoelectric prostheses have proved to be useful, the majority of amputees have not been satisfied with their function. As an amputee becomes a better user, they request not only simple tasks but also complicated ones. As a consequence, the amputee comes to know the limits of their myoelectric prosthesis, thus expectations for superior prostheses will arise. The recent remarkable development of engineering technology has enabled the progress of prosthetic limb technology, leading to the production of far superior functional prostheses which meet the user's expectations. However, there is a paradox in developing such superior prostheses. The more advanced the prosthesis we produce, the higher the cost. To achieve this end, it is absolutely imperative to secure the cooperation of both clinicians and engineers. Furthermore, a rehabilitation strategy for patients with a higher level of amputation(trans-humeral amputation, shoulder disarticulation)remains unsolved. In this paper, we propose a “Hybrid Myoelectric Prosthesis”, which consists of a myoelectric hand as a terminal device and a body-powered active elbow joint, as a realistic solution for higher level amputees. In addition, we introduce Targeted Reinnervation (TR) as a future strategy for reference.

The prosthetic rehabilitation and training of myoelectric signal for upper limb stumps / 中华物理医学与康复杂志

Objective To evaluate the effect of prosthetic rehabilitation and analyze the exercise training program with myoelectric signal for upper limb stumps.Methods Twenty canes with 22 upper limb stumps were treated with exercise for strength training,muscle contraction and control training and the complication of stump were managed.The myoelectrlc signal of upper limb stumps were detected and the stumps were trained with electronic biofeedback software system,including basic signal of biofeedback training and visual biofeedback training.Then the myoelectric prostheses were assembled.Results After prosthetic rehabilitation and myoelectfic signal training,there Wan no significant atrophy of muscle of stumps,muscle strength and range of motion of these twenty limb stumps increased.The amputees could control muscle contraction and grasp,pinch,wrist rotation,elbow extension or flexion consciously.Twenty myoelectrie prostheses were assembled.Conclusion The prosthetic rehabilitation and myoelectric signal training of limb stump is important for assembling myoelectric prosthesis.

Amputation of Four Limbs and Prosthetics A Clinical Comparison Between Myoelectric Prosthesis and Conventional Prostheisis / 대한정형외과학회잡지

Amputation is an unpleasant affair, generating a very negative aura that must be consciously combated. For optimal care of amputation, the surgeon needs not only to be comprehensive trained in reconstructive surgery but also to be knowledgeable about prosthetics. The evolution of an artificial arm can be traced first from the cosmetic prosthesis, then to that with passive movements, and lastly to an artificial limb with active movement which made it possible to restore to some degree the lost function of the amputation limb. But the gap between basic requirement of function and cosmesis is still present in conventional prosthesis. Myoelectric prosthesis was introduced for upper extremity amputees since 1960 by Korbinski and his co-workers and was most exciting improvement in the field of prosthetics. Two patients of bilateral above-elbow and bilateral below-knee amputees with myoelectric prostheses and conventional prostheses were compared in their function, cosmesis and acceptability of patient. Myoelectric prosthesis shows not only favorable cosmesis but also excellent function in range of motion and coordination of mechanical joints. And myoelectric prosthesis provides superior pinch force and requires less energy expenditure than a body-powered conventional prosthesis. So, in spite of the high cost of the appliance and of continued maintenance and repair, improvement in comfort, cosmesis and function have had to good level of acceptance of patients. Further research will undoubtedly improve the appearance, function and durability of the present electrically powered myoelectric prosthesis, making them even more acceptable and useful to lower limb and upper limb amputees.