A Broadband Biosensor With High Sensitivity up to 110 GHz for Single Cell

This article presents a novel single-cell biosensor with pico-liter scale sensitivity. The high-sensitivity microwave biosensor integrates a microchannel and a coplanar waveguide (CPW) to facilitate the capture and release of single cells. This biosensor can identify and differentiate solution concentrations, various particles, and tumor cells by measuring the amplitude and phase of the transmission coefficient. The CPW structure enhances the electric field intensity in the sensing area by increasing capacitance, which reduces the sensing area size and improves sensor sensitivity. By measuring the amplitude and phase of the wide-band transmission coefficients of tumor cells, we achieved identification of subtle changes in the electrical properties of different cell types. The sensor is capable of detecting individual particles and cells. To validate its performance, we measured different concentrations of bovine serum albumin (BSA) solution, achieving a 0.5° phase difference, confirming the sensor’s capability to recognize minor changes in pico-liter samples. The measurement of three types of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10~\mu $ </tex-math></inline-formula>m particles verified the sensor’s ability to capture, release, and distinguish between different particle types. Measurements of three cell types showed that despite their small differences, the sensor could still distinguish them. Statistical results from 20 repeated measurements demonstrate the sensor’s feasibility in distinguishing single cells. This noninvasive, label-free sensor holds significant potential for tumor cell recognition, differentiation, and diagnosis.