Multi-layer processed probes for permittivity measurement

Probes fabricated using multi-layer process are proposed for complex permittivity measurements in microwave frequency range. For multi-layer processing, we have considered LTCC (low temperature co-fired ceramic) and MEMS (micro-electro-mechanical systems) process to make the probe smaller and thus to be applicable to small biological tissues. We expect the probe size can be reduced to 0.1mm by 0.2mm if necessary. We also investigate the shielding effect of vias that is normally used to support TEM wave inside the planar transmission line structure. The complex permittivity of 0.9% saline in microwave frequency range (100MHz-40GHz) was measured using MEMS and LTCC probe to verify the usefulness of the propose probes.