Fabrication of a strain sensor for bone implant failure detection based on piezoresistive doped nanocrystalline silicon

P. Alpuim, S. A. Filonovich, P. F. Rocha, M. I. Vasilevskiy, S. Lanceros-Mendez, C. Frias, A. Torres Marques, R. Soares, C. Costa

    Research output: Contribution to journalArticlepeer-review


    One common complication following total-hip-replacement arthroplasty - one of the most performed elective surgical procedures - is the loosening of the prosthetic stem and cup, responsible for more than 80% of non-successes. A combination of piezoelectric and piezoresistive materials in a sensing device for dynamical and quasi-static analysis of the implant internal environment is envisaged by the authors. In this paper, thin-film piezoresistive millimeter-long strain sensors fabricated on flexible plastic substrates using n- and p-type hydrogenated nanocrystalline silicon films with gauge factor GF ∼ -30 and +20, respectively, are reported. A maximal value of GF = -43 is theoretically predicted for isotropic n-type multicrystalline Si. A sensor consists of an array of piezoresistors, each connected to a Wheatstone bridge-type external circuit, and to the control electronics. A sensitivity of 30 mV/μm was achieved in sensors bearing both longitudinal and transverse orientations of the resistors relative to the strain direction. Used as a shape sensor the device was able to map the contour of the hip implant. Cell growth tests show that osteoblasts grow faster on P-doped nc-Si:H thin films than on the control sample. Genotoxicity tests show that cell DNA is preserved if cultured in contact with n-type nanocrystalline silicon. © 2008 Elsevier B.V. All rights reserved.
    Original languageEnglish
    Pages (from-to)2585-2589
    Number of pages4
    JournalJournal of non-crystalline solids
    Issue number19-25
    Publication statusPublished - 1 May 2008


    • 73.50.Dn
    • 73.63.Bd
    • 84.37.+q
    • 87.19.St
    • Chemical vapor deposition
    • Conductivity
    • Microcrystallinity
    • Nanocrystals
    • Sensors
    • Silicon


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