Multi-source Harvesting Systems for Electric Energy Generation on Smart Hip Prostheses - Biomedical Engineering Systems and Technologies - page 59

Multi-source Harvesting Systems for Electric Energy
Generation on Smart Hip Prostheses

Marco P. Soares dos Santos 1 , Jorge A.F. Ferreira 1 ,A.Ramos 1 , Ricardo Pascoal 1 ,
Raul Morais dos Santos 2 , 3 , Nuno M. Silva 2 ,JoseA.O.Simoes 1 , M.J.C.S. Reis 4 ,
Antonio Festas 1 , and Paulo M. Santos 2

1 Department of Mechanical Engineering, University of Aveiro, Aveiro, Portugal
2 UTAD - University of Tras-os-Montes e Alto Douro, Vila Real, Portugal
3 Center for the Research and Technology of Agro-Environmental and Biological Sciences,
Vila Real, Portugal
4 Institute of Electronics and Telematics Engineering of Aveiro/UTAD, Vila Real, Portugal
[e-mail]

Abstract. The development of smart orthopaedic implants is being considered
as an effective solution to ensure their everlasting life span. The availability of
electric power to supply active mechanisms of smart prostheses has remained
a critical problem. This paper reports the first implementation of a new con-
cept of energy harvesting systems applied to hip prostheses: the multi-source
generation of electric energy. The reliability of the power supply mechanisms
is strongly increased with the application of this new concept. Three vibration-
based harvesters, operating in true parallel to harvest energy during human gait,
were implemented on a Metabloc TM hip prosthesis to validate the concept. They
were designed to use the angular movements on the flexion-extension, abduction-
adduction and inward-outward rotation axes, over the femoral component, to gen-
erate electric power. The performance of each generator was tested for different
amplitudes and frequencies of operation. Electric power up to 55 μ J/s was har-
vested. The overall function of smart hip prostheses can remain performing even
if two of the generators get damaged. Furthermore, they are safe and autonomous
throughout the life span of the implant.

1 Introduction

1.1 Scope of the Problem and Background

Currently, there is no cure for most causes of failure of total joint replacement, ex-
cept surgical revision [1]. Although drug administration, such as through antimicrobial
therapy, suppressive antibiotic therapy, outpatient parenteral antimicrobial therapy and
antibiotic prophylaxis, are being used to hinder progressive failure following joint re-
placement [2], surgical revisions have been the only “medical prescription” for most
causes of failure [1]. However, these surgical procedures are not therapeutic methods
which are performed to cure or to prevent early failures, but only to relieve pain and to

The authors would like to thank the Portuguese Foundation for Science and Technology (FCT)
for their financial support under the Grant PTDC/EME-PME/ 105465/2008.