Abstract
We demonstrate that solution processed thin-film organic photodiodes (OPDs) can be used as compact and sensitive integrated detectors for antioxidant capacity screening. The OPDs were fabricated with blends of regioregular poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl C
61 butyric-acid methyl-ester (PCBM). The devices had a broadband photoresponse from 350
nm to 650
nm with a peak responsivity of 0.25 A/W at 550
nm and a dark current density of 0.59
μA/cm
2 under 10
mV bias for a device area of 1
mm
2. The signal rise and fall times of the detectors were 0.51
μs and 0.66
μs, respectively. The detectors were applied to an on-chip peroxyoxalate chemiluminescence (PO-CL) assay for antioxidant capacity determination. Antioxidant standards were injected into a stream of PO-CL reagents, resulting in a CL emission decrease that correlated with the antioxidant capacity. For the encountered CL signals the OPDs provided a comparable response to photomultiplier tubes (PMTs) commonly used in analytical applications. Antioxidant capacity screening results showed excellent consistency between the two detection methods. The compact and portable detection system is suited not only to low-cost in-the-field antioxidant capacity screening, but could have wider applications for chemiluminescence based diagnostic tests at the point-of-care.