Vertically integrated optical transducer for bio-particle detection

An optical transducer with vertical structure integrated with MEMS microfluidic device is developed for the detection of bio-particle. The system consists of optical detection part; electronics control part and microfluidic part. Integrating of these parts, using optical transducer as a label-free method can provide the diagnosis of low volume biological samples as well as leading to direct detection with no significant change in physical forms of the samples. A collimated light source of deep UV-AlGaN based LED and a SiC photodiode operating at 260 nm are utilized as a light transmitter and detector, respectively. The principle of bio-particle detection is based on absorption of ultraviolet (UV) range of DNA biological samples extracted from a Caco-2 cell in a fluidic medium. The outcomes show that the signal is detected by the SiC photodiode for the rise time of τ_r ~ 118.1371 µs which shows sufficient response time to enable the detection of the bio-particle. Testing on various samples showed that the detector has no response to non-absorbance samples such as deionized (DI) water, Tris-EDTA (TE) buffer and protein samples. However, a significant outcome in the detection of a Caco-2 cell line with the absorbance coefficient of average 0.08 a.u was achieved.