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Joint replacement surgeries have enabled motion for millions of people suffering from arthritis or grave injuries. However, over 10% of these surgeries are revision surgeries. We have first analyzed the data from the worldwide orthopedic registers and concluded that the micromotion of orthopedic implants is the major reason for revisions. Then, we propose the use of inductive eddy current sensors for in vivo micromotion detection of the order of tens of μm. To design and evaluate its characteristics, we have developed efficient strategies for the accurate numerical simulation of eddy current sensors implanted in the human body. We present the response of the eddy current sensor as a function of its frequency and position based on the robust curve fit analysis. Sensitivity and Sensitivity Range parameters are defined for the present context and are evaluated. The proposed sensors are fabricated and tested in the bovine leg.

Abstract-In this paper, band-pass filters based on the microstrip configuration and utilizing coupled defected ground structures are presented. The 50 Ω microstrip line has a gap discontinuity in the middle and characterized by stepped impedance resonators on either half. The four fractal geometries tested for defected ground are the first and second iterations of the modified Moore curve, the closed staircase curve and a dual concentric closed staircase curve. The filters have a compact size and planar geometry. The modified Moore first iteration has a measured pass band from 2.27 GHz to 11.86 GHz, whereas the second iteration has a measured pass band from 1.85 GHz to 6.71 GHz. The measured pass band of the closed staircase filter is from 2.38 GHz to 7.21 GHz. The dual-concentric closed-staircase DGS filter offers a dual-band response with the measured pass band being from 2.41 GHz to 5.01 GHz and from 5.81 GHz to 8.35 GHz. All the filters can have applications in the UWB region. A parametric study showing the effect of the various controlling parameters is also presented.

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