Fabrication of Low Cost Prosthetic Arm with Foamed Fingers
Abstract
A lot of research is happening in medical field in the area of prosthesis with a aim to reduce the cost and at the same time, the artificial limb being effective. The current work concentrates on the area of prosthetic hand. Most of the prosthetic arms currently available are motor driven and costly. There are non-powered prosthetic hand also but involve the use of elastic band on solid fingers which make the arms heavy. The current work is aimed at overcoming these difficulties by the use of EPE foamed fingers which are driven actuated by a tendon by the gesture of palm while the foam provides the necessary spring back. CAD models are prepared using proe while 3D printing is used for fabricating most of the arm. EPE is used as foam material while PLA and Acrylic are used for outer structure
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Introduction
Human hand prosthetics is an increasingly interesting area in the field of medicine. With the advent of new materials and manufacturing technologies like 3D printing, a lot of advancements took place in this area. History as well as further prospects of 3D printing are given in [1]. Various materials used in 3D printing are detailed in [2]. The codes for 3D printing are achieved by mostly slicing stl files[3] and sometimes STEP files [4]. The application of 3D printing in product design has been briefed by 3DSystems[5]. Overview as to how 3D printing can be used for various applications is given in [6]. Fabricating using special materials like SMAs can also be achieved using 3D printing [7]. Even paper pulp can also be used for 3D printing [8] thus enabling low cost fabrications. An investigation into strength of FDM models using FEM is presented in [9]. The application of 3D printing in optics is discussed in [10].
The use of 3D printing medical industry has been discussed in various technical publications. Regulatory issues of the use of 3D printing in medical industry are presented in [11]. Protolabs [12] gave a detailed overview of various manufacturing processes that can be used in low volume medical industry. It also detailed the advantage of using additive manufacturing in this area. Researchers from HCL technologies [13] and TCS [14] explained how 3D printing can be used in health care industry. These applications include printing organs, cells, skin etc. 3D Printing of tissues and organs, generation of customized prosthetics, implants, and anatomical models etc along with advantages is detailed in [15]. Use of 3D printing for proper selection of surgical procedures for cardiac surgery [16]. A similar application where additive manufacturing is used for planning surgery and preparation of customized hip replacement is discussed in [17]. Mika Salmi [18] investigated into the way of combining Medical imaging and Additive manufacturing for customized dental applications. As a part of these investigations, CAD models are created based on CT scan images based on which implants are designed and 3D printed. The use of 3D printed PLA scaffolds for cell adhesion, proliferation and differentiation of human bone-marrow mesenchymal stem cells is discussed in [19].
Conclusion
The availability of desktop 3D printers at low cost made it possible to fabricate customized prosthetic arms. The current work shows a new concept of prosthetic arm in which the regular solid 3D fingers are replaced with EPE foamed fingers. The exoskeleton of the fingers and the palm cover is 3D printed using PLA. Some parts like hand sleeve are made of thin acrylic so as to further reduce the cost by avoiding 3D printing where ever possible. EPE, by its material characteristics provides good spring back which helped in opening the grip automatically, thus avoiding the use of extra elastic bands.