Prosthetic devices: Challenges and implications of robotic implants and biological interfaces

Recent trends and challenges of surface electromyography in prosthetic applications

Surface electromyography (sEMG) meets extensive applications in the field of prosthesis in the current period. The effectiveness of sEMG in prosthesis applications has been verified by numerous revolutionary developments and extensive research attempts. A large volume of research and literature works have explored and validated the vast use of these signals in prostheses as an assistive technology. The objective of this paper is to conduct a systematic review and offer a detailed overview of the work record in the prosthesis and myoelectric interfaces framework. This review utilized a systematic search strategy to identify published articles discussing the state-of-the-art applications of sEMG in prostheses (including upper limb prosthesis and lower limb prostheses). Relevant studies were identified using electronic databases such as PubMed, IEEE Explore, SCOPUS, ScienceDirect, Google Scholar and Web of Science. Out of 3791 studies retrieved from the databases, 188 articles were found to be potentially relevant (after screening of abstracts and application of inclusion-exclusion criteria) and included in this review. This review presents an investigative analysis of sEMG-based prosthetic applications to assist the readers in making further advancements in this field. It also discusses the fundamental advantages and disadvantages of using sEMG in prosthetic applications. It also includes some important guidelines to follow in order to improve the performance of sEMG-based prosthesis. The findings of this study support the widespread use of sEMG in prosthetics. It is concluded that sEMG-based prosthesis technology, still in its sprouting phase, requires significant explorations for further development. Supplementary investigations are necessary in the direction of making a seamless mechanism of biomechatronics for sEMG-based prosthesis by cohesive efforts of robotic researchers and biomedical engineers.

Artificial-Hand Technology—Current State of Knowledge in Designing and Forecasting Changes

The subject of human-hand versatility has been intensively investigated for many years. Emerging robotic constructions change continuously in order to mimic natural mechanisms as accurately as possible. Such an attitude is motivated by the demand for humanoid robots with sophisticated end effectors and highly biomimic prostheses. This paper provides wide analysis of more than 80 devices that have been created over the last 40 years. It compares both the mechanical structure and various actuators from conventional DC motors and servomechanisms, through pneumatic muscles, to soft actuators and artificial muscles. Described measured factors include angles, forces, torques, tensions, and tactiles. Furthermore, the appropriate statistics of kinematic configuration, as well as the type or number of drive units and sensory systems, show not only recent problems, but also trends that will be followed in the future.

3D printing and amputation: a scoping review

PURPOSE

Three-dimensional (3D) printing is an innovative technology being utilized to create prostheses for individuals with limb loss. However, there is a paucity of research on the feasibility of using this technology to fabricate prostheses. A scoping review was conducted to map the literature on 3D printing and its applications in the field of amputation.

MATERIALS AND METHODS

Using a scoping review framework, a systematic literature search was conducted in three electronic databases (MEDLINE, EMBASE and CINAHL) for all indexed literature up to 29 June 2018.

RESULTS

Twenty-eight articles met the inclusion criteria. The majority of studies had small sample sizes (five participants or less; n = 20) and used a case study design (n = 17). The benefits of 3D printing technology include higher levels of customization and lower production costs. However, the functionality of 3D printed prostheses is lacking. There is also a need for more robust research designs to obtain a better understanding of the advantages and disadvantages of 3D printed prostheses and its impact on end-user outcomes.

CONCLUSIONS

The use of 3D printing technology has a number of benefits for improving the manufacturing process of devices for people with lower and upper limb loss. However, more research and technological advancements are required to fully understand the impact of this technology on patients and how it will affect their daily life. The long-term effects of this technology will also need to be investigated in order to produce a more sustainable alternative to traditional prostheses.IMPLICATIONS FOR REHABILITATIONThe use of 3D printing technology for the fabrication of prosthetics for persons with limb-loss has a number of promising features to improve the fitting and customization of these devices for this patient population.Although the costs of producing 3D printed devices is less expensive and burdensome than traditional approaches to manufacturing techniques, there is a need for additional technological advancements to improve the functionality of these devices.Future research needs to adopt more robust research designs with larger sample sizes to provide a better understanding of the viability of using 3D printing technology to improve patient outcomes.

Strain distribution on a finger link: a static simulation study

Functional prosthetics hands which have the ability to help amputees perform tasks in daily life have been developed over many years. These hands need a control system which is fed information from sensors mounted on a prosthetic hand and human-machine interface. A variety of sensors therefore been developed for the prosthetic hand to measure fingertip force, joint angle (position), object slip, texture and temperature. However, most of the strain/stress sensors are attached to the fingertip. In this paper, the potential positions for strain sensors on the side of the finger link of the prosthetic hand are investigated that, in the future, will allow for force control in a lateral or key grip. With modified links of a Southampton Hand, some promising positions for strain sensors have been determined. On some of the links, the strain sensor can be used as an indicator to show the angle of the finger during a curling operation.

Multi-motion robots control based on bioelectric signals from single-channel dry electrode

This article presents a multi-motion control system to help severe disabled people operate an auxiliary appliance using neck-up bioelectric signals measured by a single-channel dry electrode on the forehead. The single-channel dry-electrode multi-motion control system exhibits several practical advantages over its conventional counterparts that use multi-channel wet-electrodes; among the challenges is an effective technique to extract bioelectric features for reliable implementation of multi degrees-of-freedom motion control. Using both time and frequency characteristics of the single-channel dry-electrode measurements, motion commands are derived from multiple feature signals associated with concentration demands and different eye-blink actions for use in a two-level control strategy that has been developed to control predefined multi degrees-of-freedom motion trajectories. Test paradigms were designed to pre-calibrate the users' feature signals to statistically account for individual variances. Experimental trials were then carried out on able-bodied and disabled volunteers to validate the universal applicability of the algorithms. The classification success rates for two different eye-blink feature signals were approximately 95% with an average time of 2.4 s for executing a concentration feature signal. The single-channel dry-electrode-based technique has been validated on a 6-degree-of-freedom robot arm demonstrating its significant potentials to help patients suffering severe motor dysfunctions operate a multi-motion auxiliary appliance in everyday living where the ease of use is a priority.

Nanomaterial scaffolds for stem cell proliferation and differentiation in tissue engineering

Tissue engineering is a clinically driven field and has emerged as a potential alternative to organ transplantation. The cornerstone of successful tissue engineering rests upon two essential elements: cells and scaffolds. Recently, it was found that stem cells have unique capabilities of self-renewal and multilineage differentiation to serve as a versatile cell source, while nanomaterials have lately emerged as promising candidates in producing scaffolds able to better mimic the nanostructure in natural extracellular matrix and to efficiently replace defective tissues. This article, therefore, reviews the key developments in tissue engineering, where the combination of stem cells and nanomaterial scaffolds has been utilized over the past several years. We consider the high potential, as well as the main issues related to the application of stem cells and nanomaterial scaffolds for a range of tissues including bone, cartilage, nerve, liver, eye etc. Promising in vitro results such as efficient attachment, proliferation and differentiation of stem cells have been compiled in a series of examples involving different nanomaterials. Furthermore, the merits of the marriage of stem cells and nanomaterial scaffolds are also demonstrated in vivo, providing early successes to support subsequent clinical investigations. This progress simultaneously drives mechanistic research into the mechanotransduction process responsible for the observations in order to optimize the process further. Current understanding is chiefly reported to involve the interaction of stem cells and the anchoring nanomaterial scaffolds by activating various signaling pathways. Substrate surface characteristics and scaffold bulk properties are also reported to influence not only short term stem cell adhesion, spreading and proliferation, but also longer term lineage differentiation, functionalization and viability. It is expected that the combination of stem cells and nanomaterials will develop into an important tool in tissue engineering for the innovative treatment of many diseases.

A BIO-MECHANICAL DESIGNED PROSTHETIC HAND WITH MULTI-CONTROL STRATEGIES

In order to mimic the natural appearance, motion, and perception of the human hand, a bio-mechatronic approach to design an anthropomorphic prosthetic hand — HIT/DLR Prosthetic Hand has been presented. It reproduces human hand in its fundamental structure such as appearance, weight, and dimensions. Its thumb can move along a cone surface in 3D space. Similar with that of human's, it combines with abduction and adduction from palmar position to lateral position. Actuated by only one motor, the middle finger, ring finger, and little finger can envelop complex-shaped objects. In addition, the bio-mechatronic integration and cosmetic designation make it much more like a genuine human hand.

HIT/DLR Prosthetic Hand can be controlled through voice control strategy, Electromyography (EMG) control strategy, EMG, and electrocutaneous sensory feedback (ESF) close loop control strategy. In EMG control system, 10 types of hand posture are recognized through six electrodes on the basis of support vector machine (SVM). The last control strategy can help an amputee recover the grasp perception, further improve the efficiency of EMG control, and reduce the hand mis-manipulation and force delivery mistakes.

PEDOT electrochemical polymerization improves electrode fidelity and sensitivity

BACKGROUND

The goal of the authors is to restore fine motor control and sensation for high-arm amputees. They developed a regenerative peripheral nerve interface with the aim of attaining closed loop neural control by integrating directly with the amputee's residual motor and sensory peripheral nerves. PEDOT, poly(3,4-ethylenedioxythiophene), has both electrical and ionic conduction characteristics. This hybrid character could help bridge the salutatory conduction of the nervous system to an electrode. The purpose of this study was to determine whether electrodes polymerized with PEDOT have improved ability to both record and stimulate peripheral nerve action potentials.

METHODS

Impedance spectroscopy and cyclic voltammetry were performed on electrodes before and after polymerization to measure electrode impedance and charge capacity. Both recording needle and bipolar stimulating electrodes were polymerized with PEDOT. Plain and PEDOT electrodes were tested using rat (n = 18) in situ nerve conduction studies. The peroneal nerve was stimulated using a bipolar electrode at multiple locations along the nerve. Action potentials were measured in the extensor digitorum longus muscle.

RESULTS

Bench testing showed PEDOT electrodes had a higher charge capacity and lower impedance than plain electrodes, indicating significantly improved electrode fidelity. Nerve conduction testing indicated a significant reduction in the stimulus threshold for both PEDOT recording and PEDOT stimulatory electrodes when compared with plain electrodes, indicating an increase in sensitivity.

CONCLUSIONS

PEDOT electrochemical polymerization improves electrode fidelity. Electrodes that have been electropolymerized with PEDOT show improved sensitivity when recording or stimulating action potentials at the tissue-electrode interface.

Making sense of artificial hands

A review of sensors for artificial hands is presented in terms of their range, specifications and characteristics. There is a growing need for sensors due to the development of prosthetic hands that have multiple degrees of freedom requiring finger coordination into different postures. The sensing of force, position (angle), object-slip and temperature allows for the control of these hands automatically and frees the user from cognitive burden. To make the best possible use of individual sensing elements, future controllers will need to combine data from different types of sensor. They may also have an integral power supply using a small battery or harvest energy from their environment and transmit data wirelessly.

Control strategies for smart prosthetic hand technology: an overview

A chronological overview of the applications of control theory to prosthetic hand is presented. The overview focuses on hard computing or control techniques such as multivariable feedback, optimal, nonlinear, adaptive and robust and soft computing or control techniques such as artificial intelligence, neural networks, fuzzy logic, genetic algorithms and on the fusion of hard and soft control techniques. This overview is not intended to be an exhaustive survey on this topic and any omissions of other works is purely unintentional.

Exposure to titanium dioxide and other metallic oxide nanoparticles induces cytotoxicity on human neural cells and fibroblasts

The use of titanium dioxide (TiO₂) in various industrial applications (eg, production of paper, plastics, cosmetics, and paints) has been expanding thereby increasing the occupational and other environmental exposure of these nanoparticles to humans and other species. However, the health effects of exposure to TiO₂ nanoparticles have not been systematically assessed even though recent studies suggest that such exposure induces inflammatory responses in lung tissue and cells. Because the effects of such nanoparticles on human neural cells are unknown, we have determined the putative cytotoxic effects of these nanoparticles on human astrocytes-like astrocytoma U87 cells and compared their effects on normal human fibroblasts. We found that TiO₂ micro- and nanoparticles induced cell death on both human cell types in a concentration-related manner. We further noted that zinc oxide (ZnO) nanoparticles were the most effective, TiO₂ nanoparticles the second most effective, and magnesium oxide (MgO) nanoparticles the least effective in inducing cell death in U87 cells. The cell death mechanisms underlying the effects of TiO₂ micro- and nanoparticles on U87 cells include apoptosis, necrosis, and possibly apoptosis-like and necrosis-like cell death types. Thus, our findings may have toxicological and other pathophysiological implications on exposure of humans and other mammalian species to metallic oxide nanoparticles.

Tissue compatibility of biomaterials: benefits and problems of skin biointegration

The integration of biomaterials with skin is necessary to enable infection-free access to vasculature and body cavities. Also, integrating plastics and metals with skin increases options for the reconstruction of surgical and traumatic defects and enables the permanent implantation of robotic and electronic devices. Until now, attempts to integrate biomaterials with skin permanently have failed because of epidermal marsupialization and infection. This article reviews the general properties required of biomaterials to optimize integration with body tissues, the modifications that increase biocompatibility, focusing particularly on surface functionalization and the specific requirements for biomaterial integration into skin. Critical pathophysiological processes relating to biocompatibility are discussed with particular emphasis on the skin-biomaterial interface. Future directions are speculated on, in particular, the specific utility of subatmospheric pressure dressings in facilitating tissue integration into biomaterials.