Limb prosthetics and orthotics

Electroactive polymer actuators, and EPAM actuators in particular, are often called artificial muscles because of the similarity in strain and force to natural skeletal muscle. Perhaps no other actuator application conveys the notion of an artificial muscle more than those for moving natural or prosthetic limbs. 

Application of EPAM for limb prosthetics and orthotics still requires significant further development of the EPAM technology in order to address issues in scaling up stroke and force, as well as packaging issues related to reliability and safety at relatively high power levels (compared to most other applications discussed here). However, the fundamental demonstrated performance of EPAM in smaller devices shows the promise of this artificial muscle technology. The performance on a per mass and per volume basis demonstrated in smaller devices is sufficient to create actuators that can replace or augment the function of natural muscle. Other characteristics of EPAM that make EPAM well suited for such limb prosthetic and orthotic applications include  

Some proof-of-principle devices have been demonstrated and specific promising applications identified. 

In 2007, MIT professor Hugh Herr demonstrated the first powered ankle prosthetic device [8], Mechanical compliance is one key to the proper operation of an ankle prosthetic since the foot is constantly interacting with surfaces of varying compliance. The MIT ankle does not use EPAM but rather uses a linear servomotor drive (rotary motor plus a lead screw) in combination with a spring in order to achieve a controllable compliance. A similar ankle orthotic device has also been developed [9]. Replacing this relatively heavy, bulky and noisy mechanism with an EPAM actuator would be desirable. 

7 Mechanical Actuation for Active Cell Culture Assays 

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Lower- and Upper-Limb Prosthetics and Orthotics, 1992, Northwestern University Medical School, Prosthetic Orthotic Center, Chicago. 

The physical designs in prosthetic and orthotic devices have changed substantially over the past decade. One could propose that this is solely the introduction of new materials. The sockets of artificial limbs have always been fashioned to suit the individual patient, historically by carving wood, shaping... 

Childress, D. S. (1985). Historical aspects of powered limb prosthetics. Clinical Prosthetics and Orthotics, no. 9,pp. 2-13. 

Fraser, C. M. (1998). An evaluation of the use made of cosmetic and functional prostheses by unilateral upper-limb amputees. Journal of the International Society for Prosthetics and Orthotics(ISPO), vol. 22, no. 3, pp. 216-223, Dec. 

Michael, J. W. (1986). Upper-limb powered components and controls current concepts. Clinical Prosthetics and Orthotics, vol. 10, no. 2, pp. 66-77. 

Quiet operation - noise from prosthetic limbs and orthotics can be annoying and draw unwanted attention to the wearer. 

Torres-Morenos, R., Solomonidis, S.E. and Jones, D. (1992) Geometric and mechanical characteristics of the above-knee residual limb. Proc. 7th. World Cong. Int. Soc. Prosthetics Orthotics, pp. 149. 

The patient assistive devices classification includes items such as walkers, bedpans, prosthetic limbs, canes, robotics, trapeze bars, wheelchair, orthot-ics (i.e., braces and shoes), patient transfer devices, and stand assist lifts. The six items belonging to the nurse protective devices classification are gloves, face masks, patient transfer devices, hand sanitizer dispensers, mechanical lifts, and gowns. The pahent protective devices classification includes items such as listed below [4] ... 

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