Ling Yan Zhang

Tunable frequency resonant biosensors dedicated to dielectric permittivity analysis of biological cell cytoplasm

This paper presents an improved design of resonant biosensor, dedicated to dielectric analysis on biological cells at microwave frequencies. Such sensor uses the capability of microwaves to penetrate inside biological cells in order to interact with their intracellular content. Hence, individual dielectric properties of the cell cytoplasm can be known and then used as a signature of the cell pathological state (living or dead, malignant or safe...). In this paper is introduced a continuously tunable frequency sensor prototype, able to perform an accurate dielectric analysis over at least a 1GHz bandwidth while keeping enough sensitivity to detect and analyze a single cell. As a proof of concept, permittivity measurements have been led on calibrated size polystyrene beads: achieved results show good agreement with expected permittivity values. Finally experiments on Glioblastoma cells will be presented.

Loss reduction technique in ferroelectric tunable devices by laser micro-etching. Application to a CPW stub resonator in X-band

Ferroelectric materials are known to be lossy at microwaves. A local microetching technique based on laser ablation is implemented here to reduce the insertion loss of highly tunable devices fabricated on KTa1-xNbxO3 (KTN) ferroelectric thin films. The relevance of this approach is studied in X-band by comparing numerically and experimentally the performance of a frequency-tunable coplanar waveguide stub resonator before and after KTN microetching. The experimental data demonstrate a large loss reduction (by a factor 3.3), while keeping a high-frequency tunability (47%) under a moderate biasing static electric field (80 kV/cm). This approach paves the way for the design of ferroelectric reconfigurable devices with attractive performance in X-band and even beyond.