11.3 A Capacitive Biosensor for Cancer Diagnosis Using a Functionalized Microneedle and a 13.7b-Resolution Capacitance-to-Digital Converter from 1 to 100nF

A malignant tumor consists of rapidly growing cancer cells, and requires a dedicated blood supply to provide oxygen and nutrients. Therefore, vascular endothelial growth factor (VEGF), a signal protein produced by cells stimulating angiogenesis, is considered as a key biomarker in clinical diagnosis of cancers [1], [2]. There are already existing methods for the VEGF detection requiring advanced instruments and complex protocols [2]. Recently, significant progress has been achieved in biosensors for the detection and quantification of VEGF using synthetic receptors [2]. In particular, a capacitive biosensor detects the change of dielectric properties when the receptor binds to VEGF, and capacitance change can be used to quantify the reactions. However, the sensitivity of the capacitive biosensors still needs to be improved for use in cancer diagnosis.