Sujith Raman

Noninvasive Osseointegration Analysis of Skull Implants With Proximity Coupled Split Ring Resonator Antenna

A novel technique for skull implant diagnostics is presented in this paper. Specially designed highly directive antenna is used for osseointegration analysis with respect to the dielectric profile variation of the implant. The extreme dielectric constant variation of implant and bone gives a high degree of discrimination in the resonant frequency of the antenna. Special care is taken in antenna design to give a perfect matching and to keep the resonant frequency band width for different background properties. The antenna simulated on three different substrates is fabricated and experimentally verified with phantom models.

Microwave phantoms for craniotomy follow-up probe development

A novel phantom for skull implant diagnostics is presented in this paper. Specially designed three layer phantom is designed for osseointegration analysis after craniotomy using 2.4 GHz microwave probe. The phantom represents skin, skull and brain, and defects are made in the skull with the dielectric profile variation of realistic implants. The extreme dielectric constant variation of implant and bone gives a high degree of discrimination in resonant frequency. The presented craniotomy phantom is very useful for designing antennas for monitoring skull healing.

Experimental Procedure for Determination of the Dielectric Properties of Biological Samples in the 2-50 GHz Range

The objective of this paper was to test and evaluate an experimental procedure for providing data on the complex permittivity of different cell lines in the 2-50-GHz range at room temperature, for the purpose of future dosimetric studies. The complex permittivity measurements were performed on cells suspended in culture medium using an open-ended coaxial probe. Maxwells mixture equation then allows the calculation of the permittivity profiles of the cells from the difference in permittivity between the cell suspensions and pure culture medium. The open-ended coaxial probe turned out to be very sensitive to disturbances affecting the measurements, resulting in poor precision. Permittivity differences were not large in relation to the spread of the measurements and repeated measurements were performed to improve statistics. The 95% confidence intervals were computed for the arithmetic means of the measured permittivity differences in order to test the statistical significance. The results showed that for bone cells at the lowest tested concentration (33 500/ml), there were significance in the real part of the permittivity at frequencies above 30 GHz, and no significance in the imaginary part. For the second lowest concentration (67 000/ml) there was no significance at all. For a medium concentration of bone cells (135 000/ml) there was no significance in the real part, but there was significance in the imaginary part at frequencies below about 25 GHz. The cell suspension with a concentration of 1 350 000/ml had significance in the real part for both high (above 30 GHz) and low (below 15 GHz) frequencies. The imaginary part showed significance for frequencies below 25 GHz. In the case of an osteosarcoma cell line with a concentration of 2 700 000/ml, only the imaginary part showed significance, and only for frequencies below 15 GHz. For muscle cells at a concentration of 743 450/ml, there was only significance in the imaginary part for frequencies below 5 GHz. The experimental data indicated that the complex permittivity of the culture medium may be used for modeling of cell suspensions.

Microstrip patch based switched beam antenna at 2.45 GHz for wireless sensor network applications

Abstract The design and development of a switched beam antenna at 2.45 GHz industrial, scientific and medical band for wireless sensor network applications is presented in this paper. The antenna is capable of switching the beam pattern in directions such as in the boresight direction 0°, ±63° and as a bidirectional endfire radiator (±85°). The directive gain of the antenna is 3.9, 5.8 and 5.8 dBi in respect to those angles. The shift in the resonance frequency is found to be negligible irrespective of the direction of the switched beam. The realized gain of the proposed antenna in the steering direction is found to be better than a standard microstrip patch antenna on the same size of the substrate and ground plane. The antenna was designed and optimized through simulations using CST microwave studio and the prototype was experimentally tested using R&S ZVB8 network analyser.

Osseointegration analysis of skull implants using microstrip fed split ring resonator antenna

A microwave technique for skull implant curing analysis is presented here. A microstrip antenna is used for osseointegration analysis with respect to the dielectric profile variation of the implant. The bone and implant gives a high degree of discrimination in resonant frequency of reflection coefficient. The prototype is designed to retain the impedance matching at all implant conditions and even in normal phantom. The antennas simulated on three different substrates layers are fabricated and concept is experimentally verified with phantom models.

Geometrical and dimensional dependance of skull implants on oseointegration analysis using microwave probe

This paper present the geometrical and dimensional dependence of implants during the healing analysis. The healing analysis is done using microwave antenna based on a split ring resonator. Microwave antenna for osseointegration is done for the first time. The prototypes fabricated in three different substrates are measured using head phantoms with different implant geometry and dimension. The knowledge about the dependency on implant geometry and dimension is useful for the surgeons to have a proper selection of implants.