Design of a 3D-printed hand prosthesis featuring articulated bio-inspired fingers

Abstract

Various upper-limb prostheses have been designed for 3D printing but only a few of them are based on bio-inspired design principles and many anatomical details are not typically incorporated even though 3D printing offers advantages that facilitate the application of such design principles. We therefore aimed to apply a bio-inspired approach to the design and fabrication of articulated fingers for a new type of 3D printed hand prosthesis that is body-powered and complies with basic user requirements. We first studied the biological structure of human fingers and their movement control mechanisms in order to devise the transmission and actuation system. A number of working principles were established and various simplifications were made to fabricate the hand prosthesis using a fused deposition modelling (FDM) 3D printer with dual material extrusion. We then evaluated the mechanical performance of the prosthetic device by measuring its ability to exert pinch forces and the energy dissipated during each operational cycle. We fabricated our prototypes using three polymeric materials including PLA, TPU, and Nylon. The total weight of the prosthesis was 92 g with a total material cost of 12 US dollars. The energy dissipated during each cycle was 0.380 Nm with a pinch force of ≈16 N corresponding to an input force of 100 N. The hand is actuated by a conventional pulling cable used in BP prostheses. It is connected to a shoulder strap at one end and to the coupling of the whiffle tree mechanism at the other end. The whiffle tree mechanism distributes the force to the four tendons, which bend all fingers simultaneously when pulled. The design described in this manuscript demonstrates several bio-inspired design features and is capable of performing different grasping patterns due to the adaptive grasping provided by the articulated fingers. The pinch force obtained is superior to other fully 3D printed body-powered hand prostheses, but still below that of conventional body powered hand prostheses. We present a 3D printed bio-inspired prosthetic hand that is body-powered and includes all of the following characteristics: adaptive grasping, articulated fingers, and minimized post-printing assembly. Additionally, the low cost and low weight make this prosthetic hand a worthy option mainly in locations where state-of-the-art prosthetic workshops are absent.

A Review of Conductive Carbon Materials for 3D Printing: Materials, Technologies, Properties, and Applications

“…After years of development and later innovation, the 3D printing technology has derived new printing methods, such as biological 3D printing [ 106 ], and solvent casting 3D printing [ 107 , 108 ], etc. These new printing methods have been gradually applied in biological applications [ 109 , 110 ], electronics [ 111 ], wearable devices [ 112 , 113 ], and other fields. Conductive polymer nanocomposites (CPNs) prepared with traditional silver nanoparticles as fillers have good electrical conductivity, but the use of plenty of precious metal silver also restricts its application in industry.…”

Simplified prosthetic rehabilitation of a patient with partial finger amputation after a firearm injury

“…6 Lost limbs can be rehabilitated with articulated prostheses, facilitating the patient's function. [6][7][8] However, conventional robotics, with rigid and heavy materials, such as metals, loses in the esthetic aspect and is a disadvantage in the case of finger prostheses. Lighter and more flexible prostheses are being studied to combine articulated mechanics and esthetics.…”

“…Prostheses with the ability to generate sensory feedback to the patient are being developed, an interesting feature for larger amputated regions, such as the hands. [5][6][7][8] These robotic prostheses can facilitate the apprehension of objects because they can be articulated, unlike conventional prostheses that are more rigid. However, this is not the reality of many centers around the world, and the conventional technique presents excellent clinical results.…”

Additive Manufacturing of Biomaterials—Design Principles and Their Implementation

“…PLA materials can also be used to form moulds that can later be used to create soft mechanical metamaterials with shape-matching properties [ 95 ] ( Figure 3 d). Furthermore, PLA materials can be used for the design and fabrication of low-cost prosthetics, such as hand prosthesis and artificial fingers ( Figure 3 e) [ 365 ], and non-assembly mechanisms for medical devices [ 366 , 367 ].…”

“… ( a – c ) Shape-shifting of the shape-memory polymers, i.e., ( a ) self-twisting: after activation, two flat self-twisting strands form a DNA-inspired shape, ( b ) self-bending: on activation, a flat printed construct is folded into a cubic box, and ( c ) sequential shape-shifting: folding the initially flat petals into a tulip in two steps by controlling the printing directions at specific locations (i.e., A, and B); the time lapses show the folding sequence for both designs (reproduced from Ref. [ 176 ] with permission from the Royal Society of Chemistry); ( d ) shape matching of the scapula with a specimen fabricated by three zones of auxetic, transition, and conventional unit cells [ 95 ]; ( e ) 3D-printed hand prosthesis [ 365 ]; ( f ) buckling-driven soft mechanical metamaterials for external prosthetics and wearable soft robotics, such as exoskeletons and exosuits (reproduced from Ref. [ 98 ] with permission from the Royal Society of Chemistry); ( g – i ) cell culture using submicron patterns: ( g ) a schematic view of the two-photon polymerisation method [ 368 ]; ( h ) SEM image showing submicron-scale topographies incorporated into a porous micro-scaffold [ 368 ] with ( i ) cells cultured on patterned surfaces after 2 and 4 days of cell culture [ 369 ].…”