Fig. 1: Schematics illustrating the mechanism of electrochemical micro-aptasensors based on hybridization chain reaction (HCR).

a Procedures for preparing biotin-labeled HCR exosomes. b, top Modification of microelectrodes with CD63. b, bottom A photo of a fabricated electrochemical micro-aptasensor with CD63-modified electrodes and a microfluidic chamber. c The working mechanism of electrochemical micro-aptasensors.