Circulating tumor cells in human peripheral blood play an important role in
cancer metastasis. In addition to the size-based and antibody-based capture and separation of
cancer cells, their electrical characterization is important for rare cell detection, which can prove fatal in point-of-care testing. Herein, an organic electrochemical transistor (OECT) biosensor made of
solution-gated carboxyl
graphene mixed with
PEDOT:PSS for the detection of
cancer cells in situ is reported. Carboxyl
graphene was used in this work to modulate
cancer cell morphology, which differs significantly from normal blood cells, to achieve rare
cancer cell detection. When the concentration of carboxyl
graphene mixed in
PEDOT:PSS was increased from 0 to 5 mg mL-1, the
cancer cell surface area increased from 218 μm2 to 530 μm2, respectively. A change in cell morphology was also detected by the OECT. Negative charges in the
cancer cells induced a positive shift in gate voltage, which was approximately 40 mV for spherical-shaped cells. When the cell surface area increased, transfer curves of transistor revealed a negative shift in gate voltage. Therefore, the sensor can be used for in situ detection of
cancer cell morphology during the cell capture process, which can be used to identify whether the captured cells are deformable.