| dc.description.abstract | With the development of osseointegration of implants, implant placement has been extended from dental implants to amputation implants, and the success of the surgery is judged by the osseointegration (stability of the implant).
When implants are placed in bone, they are considered as cantilever beam structures. The better the osseointegration, the stronger the rigidity, and the higher the resonance frequency; on the contrary, the lower the resonance frequency. In this study, we developed a Raspberry Pi-based implant osseointegration detection device, which has the advantages of small size and handheld type. Validation was performed using the standard structure Testpeg® manufactured by Osstell® and an osseointegration model designed for limb implant surgery. The device provided objective and quantitative values to establish an osseointegration assessment method compared to previous commercial data acquisition cards and industrial computer results.
Through the detection device, the AC sweeping signal is input to the inductor, which generates alternating magnetic field excitating the structure. The resonance frequency of the cantilever beam structure was calculated from the frequency response function by the probe detecting the magnetic force change. Two types of probes were used to measure the same structure: (1) dual inductor pair type and (2) dual inductor-Hall IC type. The difference between two probes lies in the components for detecting the magnetic field change, the dual inductor pair type converts the magnetic field change into telecommunication signal output through Faraday′s law; the dual inductor-Hall IC type converts the magnetic field change into telecommunication signal output through Hall effect.
The sensitivity of the two types of probes, the distance between the excitation source and the structure to be assessed, and the response range were compared, the sensitivity of the dual inductor pair probe varies with the signal frequency at the same magnetic field, from 2 .8mV/G at 1 kHz to 24.5 mV/G at 10 kHz. The dual inductor-Hall IC probe maintains 1.5 mV/G at all frequencies, and overall the dual inductor pair type has better sensitivity than the dual inductor-Hall IC type.
The dual inductor pair type probe has no limitation on the magnetic field strength of the structure to be measured, while the dual inductor-Hall IC type probe requires confirmation of the Hall IC measurement range. For example, in this study, the measurement range is ±1000 Gauss, beyond which the magnetic field change cannot be correctly responded to.
Comparing the distance between the excitation source and the structure to be assessed, the dual inductor pair type probe is 4.2 mm; the dual inductor-Hall IC type probe is 2.5 mm, and comparing the peak-valley differences of the frequency response function drop point, the amplitude of the dual inductor-Hall IC type probe on different structures is greater than the dual inductor pair type probe by more than 10 times, which proves that the dual inductor-Hall IC type probe has better excitation capability.
In summary, the dual inductor-Hall IC type was superior to the dual inductor-Hall IC type in terms of magnetic field range and sensitivity, but the dual inductor-Hall IC type was superior to the dual inductor pair in terms of excitation capability. Both types of probes can measure the resonant frequency in Testpeg®, among which the dual inductor-Hall IC type is more effective. In the goat femoral amputation model, the dual inductance-Hall IC type could not be measured because the magnetic field strength of the permanent magnet on the structure to be assessed exceeded the measurement range. Only the dual inductor pair type can measure the resonance frequency, and the results can fully reflect the harder interface tissue (better osseointegration) with higher resonance frequency values.
The business card-sized Raspberry pi device reduces the size of the device and displays the frequency response graph and resonance frequency through the user interface, making it easy to carry and use. The input signal of the device is set at 3 V, 1-10 kHz sweep signal and the measurement distance is 1 mm.
The resonance frequency of Testpeg® can be measured below 6000Hz, the resonance frequency cannot be displayed correctly on the limb osseointegration model due to the low resolution. | en_US |