uGrip II: A novel functional hybrid prosthetic hand design Ashley Polhemus, Brianne Doherty, Kevin Mackiw, Rajan Patel, and Manish Paliwal Biomedical Engineering Department The College of New Jersey Ewing NJ, United States Polhemu2@tcnj.edu , Dohert2@tcnj.edu , Mackiw2@tcnj.edu , Patel243@tcnj.edu , Paliwal@tcnj.edu Abstract—Current prosthetic devices frequently offer limited function at high costs. This proof-of-concept design proposes a hybrid trans-radial prosthesis that uses gross body movements to control multiple degrees of freedom. The novel actuation system uses signals transduced from shoulder articulations to control pneumatic actuators, which power the hand. Keywords- Body Powered, Hand, Hybrid, Pneumatic, Prosthesis, Trans-radial Amputee, Introduction Each year, approximately 41,000 upper limb amputations occur in the US alone 1 . This number is expected to increase by 151% by 2050 2 . Currently, three types of prosthetics are readily available: cosmetic, body powered and myoelectric 1 . Cosmetic prostheses are nonfunctional, but are inexpensive and aesthetically pleasing. Body powered devices permit only one degree of freedom, and cause physical strain on the user. Myoelectric prostheses are highly functional but are costly. In addition, learning to use a myoelectric device is complicated and frustrating for users. To address the shortcomings of current designs, the proposed hybrid prosthetic hand will translate body movements into electrical signals, triggering a desired motion. The hybrid design allows for controlled wrist rotation, wrist flexion, conforming grip, and pinch grip. Further, manually controlled features in the proposed design allow users to the pivot the thumb joint between two positions. The proposed trans-radial prosthesis replicates many core functions of a human hand while minimizing cost. I. DESIGN A novel control mechanism and multifunctional prosthetic hand allowing for seven degrees of freedom was developed for trans-radial amputees [Fig. 1]. The mechanism may aid in the development of highly functional, user friendly, and cost effective prostheses. A pneumatic actuation system comprised of a pneumatic rotary actuator, pneumatic artificial muscles (PAMs), and solenoid valves allows for a lightweight, and highly functional alternative for a prosthetic hand at a low cost. In a national survey of amputees, 80% of subjects indicate harness comfort must be improved 3 . The hybrid system minimizes harness loading and prevents strain on the user. Further, users desire improved functionality and more degrees of freedom, namely wrist movement 4 . Natural wrist motions typically require 180°of rotation, and up to 45° of flexion 5 . Anthropomorphic prostheses are socially advantageous, so the dimensions of the fingers and palms have been kept within the 5 th and 95 th percentiles of normal hands 6 . The grip force generated by each finger is greater than 4.45N (1 lb) 7 . The device allows for 90° each of wrist rotation, wrist bending, and thumb rotation. In addition, the prosthetic maintains an anthroporphic design. The individual component design is as follows: a. Finger and Palm Design Device fingers consist of three segments, simulating the three phalanges of a human finger. Torsion springs return fingers to a fully extended state when the device is unengaged, allowing for a voluntary-closed grip configuration. Fingers are controlled simultaneously by four PAMs routed to a common reservoir, allowing even force distribution and independent actuation. A compact anthropomorphic palm was designed to minimize weight and optimize gripping area while housing the thumb actuation mechanism. Optimal dimensions were determined to be 6.604 cm (2.6 in.) by 9.53 cm (3.75 in.). A removable Figure 1. Proposed design and testing mount. (A) Thumb rotation mechanism, (B) pneumatic rotary actuator, (C) pneumatic artificial muscles, and (D) testing mount are indicated. Pneumatic tubing and ball bearing are excluded to show wrist assembly. A B C D 2013 39th Annual Northeast Bioengineering Conference 978-0-7695-4964-4/13 $26.00 © 2013 IEEE DOI 10.1109/NEBEC.2013.148 303