Design Criteria of Soft Exogloves for Hand Rehabilitation- Assistance Tasks

This paper establishes design criteria for soft exogloves (SEG) to be used as rehabilitation or assistance devices. This research consists in identifying, selecting, and grouping SEG features based on the analysis of 91 systems that have been proposed during the last decade. Thus, function, mobility, and usability criteria are defined and explicitly discussed to highlight SEG design guidelines. Additionally, this study provides a detailed description of each system that was analysed including application, functional task, palm design, actuation type, assistance mode, degrees of freedom (DOF), target fingers, motions, material, weight, force, pressure (only for fluids), control strategy, and assessment. Such characteristics have been reported according to specific design methodologies and operating principles. Technological trends are contemplated in this contribution with emphasis on SEG design opportunity areas. In this review, suggestions, limitations, and implications are also discussed in order to enhance future SEG developments aimed at stroke survivors or people with hand disabilities

Cost-Effective Prosthetic Hand for Amputees: Challenges and Practical Implementation

According to statistics, approximately 160,000 people in Malaysia, out of the current population of 32 million, need prosthetic or orthotic equipment. For individuals who have experienced upper extremity amputations, significant challenges are posed by the loss of functionality and the desire for a cosmetically appealing solution. To address this issue, a cost-effective prosthetic hand was proposed and developed. An overview of existing prosthetic hands is also offered, with an emphasis on cost-effectiveness, challenges, strengths, and weaknesses. The developed prosthetic hand incorporates a practical and underactuated finger mechanism. It is equipped with controllers based on EMG sensors to ensure that optimal responses are achieved during the grasping and releasing of objects. A suitable motor was carefully chosen to facilitate effective grasping and ungrasping activities. The proposed design was realized using SolidWorks and a 3D Printer. The capabilities of the prosthetic hand were demonstrated through a series of tests involving various objects, including pliers, a screwdriver, and a phone. The results indicate that objects of different sizes and shapes can be effectively grasped and ungrasped by the prosthetic hand. The unique bending angles in each finger result from the way tendons are connected via flexible cords and fishing lines to the servo motor. This design allows for a dynamic response based on the user's muscle flex and strength. The affordability of this cost-effective prosthetic hand demonstrates its potential as a practical and viable solution for amputees aiming to restore their grasping functionalities

Cost-Effective Prosthetic Hand for Amputees: Challenges and Practical Implementation

According to statistics, approximately 160,000 people in Malaysia, out of the current population of 32 million, need prosthetic or orthotic equipment. For individuals who have experienced upper extremity amputations, significant challenges are posed by the loss of functionality and the desire for a cosmetically appealing solution. To address this issue, a cost-effective prosthetic hand was proposed and developed. An overview of existing prosthetic hands is also offered, with an emphasis on cost-effectiveness, challenges, strengths, and weaknesses. The developed prosthetic hand incorporates a practical and underactuated finger mechanism. It is equipped with controllers based on EMG sensors to ensure that optimal responses are achieved during the grasping and releasing of objects. A suitable motor was carefully chosen to facilitate effective grasping and ungrasping activities. The proposed design was realized using SolidWorks and a 3D Printer. The capabilities of the prosthetic hand were demonstrated through a series of tests involving various objects, including pliers, a screwdriver, and a phone. The results indicate that objects of different sizes and shapes can be effectively grasped and ungrasped by the prosthetic hand. The unique bending angles in each finger result from the way tendons are connected via flexible cords and fishing lines to the servo motor. This design allows for a dynamic response based on the user's muscle flex and strength. The affordability of this cost-effective prosthetic hand demonstrates its potential as a practical and viable solution for amputees aiming to restore their grasping functionalities

Soft Gloves: A Review on Recent Developments in Actuation, Sensing, Control and Applications

Interest in soft gloves, both robotic and haptic, has enormously grown over the past decade, due to their inherent compliance, which makes them particularly suitable for direct interaction with the human hand. Robotic soft gloves have been developed for hand rehabilitation, for ADLs assistance, or sometimes for both. Haptic soft gloves may be applied in virtual reality (VR) applications or to give sensory feedback in combination with prostheses or to control robots. This paper presents an updated review of the state of the art of soft gloves, with a particular focus on actuation, sensing, and control, combined with a detailed analysis of the devices according to their application field. The review is organized on two levels: a prospective review allows the highlighting of the main trends in soft gloves development and applications, and an analytical review performs an in-depth analysis of the technical solutions developed and implemented in the revised scientific research. Additional minor evaluations integrate the analysis, such as a synthetic investigation of the main results in the clinical studies and trials referred in literature which involve soft gloves

Anthropomorphic Twisted String-Actuated Soft Robotic Gripper with Tendon-Based Stiffening

Realizing high-performance soft robotic grippers is challenging because of the inherent limitations of the soft actuators and artificial muscles that drive them, including low force output, small actuation range, and poor compactness. Despite advances in this area, realizing compact soft grippers with high dexterity and force output is still challenging. This paper explores twisted string actuators (TSAs) to drive a soft robotic gripper. TSAs have been used in numerous robotic applications, but their inclusion in soft robots has been limited. The proposed design of the gripper was inspired by the human hand. Tunable stiffness was implemented in the fingers with antagonistic TSAs. The fingers' bending angles, actuation speed, blocked force output, and stiffness tuning were experimentally characterized. The gripper achieved a score of 6 on the Kapandji test and recreated 31 of the 33 grasps of the Feix GRASP taxonomy. It exhibited a maximum grasping force of 72 N, which was almost 13 times its own weight. A comparison study revealed that the proposed gripper exhibited equivalent or superior performance compared to other similar soft grippers.Comment: 19 pages, 15 figure

Stretchable metallization technologies for skin-like transducers

The skin is not only the largest human organ, capable of accomplishing distributed and multimodal sensing functions. Replicating the versatility of skin artificially is a significant challenge, not only in terms of signal processing but also in mechanics. Stretchable electronics are an approach designed to cover human and artificial limbs and provide wearable sensing capabilities: motion sensors distributed on the hand of neurologically impaired patients could help therapists quantify their abilities; prostheses equipped with multiple tactile sensors could enable amputees to naturally adjust their grasp force. Skin-like electronic systems have specific requirements: they must mechanically adapt to the deformations imposed by the body they equip with minimal impediment to its natural movements, while also providing sufficient electrical performance for sensor transduction and passing electrical signals and power. A metallization ensuring stable conductivity under large strains is a prerequisite to designing and assembling wearable circuits that are integrated with several types of sensors. In this work, two innovative metallization processes have been developed to enable scalable integration of multiple sensing modalities in stretchable circuits. First, stretchable micro-cracked gold (Au) thin films were interfaced with gallium indium eutectic (EGaIn) liquid metal wires. The Au films, thermally evaporated on silicone elastomer substrates, combined high sheet resistance (9 to 30 Ohm/sq) and high sensitivity to strain up to 50%. The EGaIn wires drawn using a micro-plotting setup had a low gauge factor (2) and a low sheet resistance (5 mOhm/sq). Second, a novel physical vapor deposition method to deposit of thin gallium-based biphasic (solid-liquid) films over large areas was achieved. The obtained conductors combined a low sheet resistance (0.5 Ohm/sq), a low gauge factor (~1 up to 80% strain), and a failure strain of more than 400%. They could be patterned down to 10 µm critical dimensions. Skin-like sensors for the hand were assembled using the two processes and their capabilities were demonstrated. Thin (0.5 mm) silicone strips integrating EGaIN wires and micro-cracked Au strain gauges were mounted on gloves to encode the position of a biomimetic robotic finger and a human finger. In combination with soft pressure sensors, they enabled precise grasp analysis over a limited range of motion. Then, biphasic films were micro-patterned on silicone to assemble 50 µm thin epidermal strain gauges. The strain gauges were attached on a user's finger and accurately encoded fine grasping tasks covering most of the human hand range of motion. The biphasic films were also used to power wireless MEMS pressure sensors integrated in a rubber scaffold. The device was mounted on a prosthetic hand to encode normal forces in the 0 N to 20 N range with excellent linearity. The epidermal strain sensors are currently being used to quantify the tremors of patients with Parkinson's disease. In the future, the unique properties of the biphasic films could enable advanced artificial skins integrating a high density of soft transducers and traditional high-performance circuits