Finch: Prosthetic Arm With Three Opposing Fingers Controlled by a Muscle Bulge

Abstract

Forearm amputees can use body-powered hooks and myoelectric hands for their daily activities. The body-powered hooks are suitable for delicate manipulation. However, their appearance is not always preferred by amputees, and a harness to pull a control cable is not easy to wear. Although the myoelectric hands have a natural appearance similar to the human hand and can be intuitively controlled by a myoelectric control system, they are not easy to try out and are heavy. This paper reports on the Finch, a prosthetic arm with three opposing fingers controlled by a muscle bulge. The aim of developing the Finch is to realize a lightweight prosthetic arm that is easy to wear and use. Three opposing fingers are controlled according to the degree of muscle bulge measured with a muscle bulge sensor on the user's forearm caused by muscle contraction. A supporter socket, consisting of a resin socket frame and a fabric supporter, allows easy fitting. A simple design using a linear actuator and 3D-printed parts achieved light weight (330 g) and low cost. Six functional tests and user tests using Southampton Hand Assessment Procedure showed that the Finch had a practical function that could be used in daily activities.

Developing a Novel Prosthetic Hand with Wireless Wearable Sensor Technology Based on User Perspectives: A Pilot Study

“…While various types of functional myoelectric hands are currently available, their acquisition and sustained use are impeded by several barriers [2][3][4][5][6], chiefly due to increased costs [7,8]. Individuals with upper-limb deficiencies often face challenges in procuring electrically powered prostheses without government assistance owing to their considerable costs; additionally, only a few healthcare systems allow the prescription of myoelectric hands [9][10][11][12]. In Japan, myoelectric prostheses are prescribed with government support only in extremely limited circumstances [11].…”

“…Funding structures responsible for prescribing prostheses vary internationally as well as regionally and depend on prosthetic users' backgrounds, such as age and occupation. The abandonment of prostheses is another concern [2,[4][5][6]13,14], which is often related to funding [12]. The weight of myoelectric prostheses is a contributing factor to their discontinued use [5,6,8,13].…”

“…In addition, individuals with short residual or paralyzed limbs cannot operate conventional myoelectric hands, which are designed to detect muscle activity in residual limbs [12,16]. Electrodes placed in residual parts of the limbs may aggravate pain in individuals with upper-limb deficiencies and sensory disturbances.…”