A label-free and non-invasive CMOS sub-THz plasmonic sensor for circulating tumor cell detection

This paper presents a label-free and non-invasive plasmonic sensor based on electrical cell impedance detection at sub-THz. The plasmonic sensor implemented by split-ring resonator (SRR) with different topologies is investigated in standard 65-nm CMOS process: differential T-line loaded SRR; stacked TEM-mode SRR and stacked TM-mode SRR. It is shown that sensor array with SRR has high sensitivity to detect the frequency shift between water and circulating tumor cells (CTCs) due to the difference in permittivity, especially for the surface-wave based TM-mode SRR. Moreover, oscillator with a voltage output is designed based on TEM-mode SRR, which is observed with a high voltage sensitivity of 15.4 mV/fF in distinguishing CTC solutions with various concentrations. Therefore, the plasmonic sensor proposed in this work is beneficial to monitor the tumor growth.