Handheld, Microwave Transmission-Based Probe: Numerical Evaluation of the Sensitivity Zone

We have developed a handheld, open-ended coaxial transmission-based probe for subsurface interrogation of in vivo human tissue. In particular, we are using it to detect and assess levels of sarcopenia - an infiltration of normal muscle with fat. The coaxial apertures are enlarged and elongated to improve signal penetration into the tissue, and early phantom studies demonstrate that the probes can detect tissue property changes as deep as 2.5 – 3.0 cm. To complement these studies, we have devised a set of simulation experiments. In this case, we extrapolate from work involving our microwave tomographic imaging development. Particularly, the Jacobian matrix used to update the images in the associated iterative algorithm involves constructing sensitivity maps corresponding to permutations of all transmitting and receiving antenna pairs. Because this new probe is transmission-based, we can utilize the same approach and develop sensitivity maps for this aperture pair. Experiments are performed in this study over a range of frequencies and confirm our previous phantom experiment results.