Fig. 7.

Schematic illustration of label-free capacitive aptasensor for HER2 protein detection in serum. a capacitor array chip, b capacitor, c gold IDE functionalized with anti-HER2 aptamer whose phosphodiester backbone contributes abundant negatively charged species on capacitors, d formation of aptamer-HER2 complex that induce charge distribution and thus influence specific changes in capacitance that can be measured and e equivalent circuit of the interdigitated capacitor sensor

(Reprinted with permission from Ref. [93]. Copyright © 2015, Elsevier)