Page 204 - Handbook of Biomechatronics

Upper-Limb Prosthetic Devices 201

1.5.3 3D Printing
3D printing is an additive manufacturing process that creates a solid physical
object from a digital design adding material layer by layer. Although 3D
printing technology has been around for >30years, only recently has
become inexpensive. A number of 3D printing technologies and materials
exist, with varying cost, and object size, strength, surface, color, etc. Among
the technologies, one can identify the following: stereolithography (SLA),
digital light processing (DLP), fused deposition modeling (FDM), selective
laser sintering (SLS), selective laser melting (SLM), electronic beam melting
(EBM), and laminated object manufacturing (LOM) (3D, n.d.). The
materials used include glass polyamide, epoxy resin, wax, and metals like
titanium, silver, and steel. Among the materials, the most popular is ABS;
however, the most promising are composites (strength, lightweight) and
metal (strength).
In upper-limb prostheses, three main prostheses parts that can benefit
from such technologies are the socket, the arm, and the hand. The benefits
of using 3D printed upper-limb devices are many and important: low cost,
customization, lightweight.
3D printing will change the fabrication of prosthetic sockets and other
limb components drastically. Current generations of 3D printers print com-
posite materials such as carbon fiber, Kevlar, or glass fiber and have the
potential to produce fully functional sockets. Latest socket developments
are capable of facilitating both implantable and multiple surface electromy-
ography sensors in traditional and osseointegration-based systems (Vujaklija
et al., 2016). Many of the open-source hands that are prone to breakage and
limited to child sizes can become fully functional at adult sizes. 3D direct
laser metal sintering machines are also beginning to be used more in the
manufacture of prosthetic components such as artificial fingers and other
customizable components (Krausz et al., 2016).
The use of inexpensive, low-end 3D printing technologies for sockets is
explored in Herberts et al. (1973). Although 3D printed objects usually are
weak and fragile, comfortable prosthetic sockets have been produced and
have been used in preliminary fittings with patients.
The first open-source 3D printed hand device was developed in 2012 in
South Africa. A charitable organization called Robohand (Fig. 15A), created
3D limb models and uses 3D printers to build lightweight custom arms,
hands, and fingers at low cost: $500–$2K (Oliker, 2015). The Robohand
demonstrated that 3D printing reduces the cost of a prosthetic extremity
(Tanaka and Lightdale-Miric, 2016). A large number of available open-