Fig. 5: Performance of low-voltage OFET miRNA sensor.
a Photo images of the fabricated OFETs on PEN substrate, and the sensor tags consisting of an encapsulated OFET and contacts for extended-gate sensing electrode and reference electrode. b Measured ID–VRef curve by sweeping VRef after the sensor being placed in the electrolyte solution, presenting an obvious shift to the negative direction compared with the ID–VGS curve of the pristine OFET. After immobilization of ssDNA probes onto the sensing electrode, there is a small shift backward due to the negatively charged probes. c Measured ID–VRef curves for the concentration of miR-21 targets varying from 0 to 1 μM. d Extracted Vth shift (ΔVth) of the curves at various concentrations of miR-21 with the test results for the 3-base mismatch miRNA as the background level. The dashed lines indicate the limit of detection (LOD) obtained from three-times the standard-measurement error bar of the blank noise. Error bars indicate standard deviations. e The measured relative current change from the background level (∆ID/ID0) at VRef = − 0.1 V for various miR-21 concentrations. Error bars indicate standard deviations.
