Laser-induced fluorescence detection platform for point-of-care testing

Abstract

Point-of-care testing (POCT) devices for continuous low-cost monitoring of critical patient parameters require miniaturized and integrated setups for performing quick high-sensitivity analyses, away from central clinical laboratories. This work presents a novel and promising laser-induced fluorescence platform for measurements in direct optical test formats that leads towards such powerful POCT devices based on fluorescence-labeled immunoassays. Ultimate sensitivity of thin film photodetectors, integrated with microfluidics, and a comprehensive optimization of all system components aim at low-level signal detection in the targeted biosensor application. The setup acquires fluorescence signals from the volume of a microfluidic channel. An innovative sandwiching process forms a flow channel in the microfluidic chips by embedding laser-cut double-sided adhesive tapes. The custom fit of amorphous silicon based photodiode arrays to the geometry of the flow channel enables miniaturization, fully adequate for POCT devices. A free-beam laser excitation with line focus provides excellent alignment stability, allows for easy and reliable swapping of the disposable microfluidic chips, and therewith greatly improves the ease of use of the resulting integrated device. As a proof-of-concept of this novel in-volume measurement approach, the limit of detection for the dye DY636-COOH in pure water as a model fluorophore is examined and found to be 26 nmol .

Serological and molecular rapid diagnostic tests for Toxoplasma infection in humans and animals

“…Laser-induced fluorescence (LIF) is another type of optical detection approach, which is broadly used for the microfluidic immunosensor design [81,82]. Recently, LIF microfluidic chips have been used in many research fields including labon-chip [83], POC testing [84,85], and organic compound analysis [86]. A microfluidic immunosensor based on LIF has been developed for the quantitative detection of IgG antibodies against T. gondii in humans [87].…”

“…Attempts have been made to exploit the potential POC benefits of microfluidics by miniaturizing and integrating the optical elements, including using amorphous silicon photodiodes [88] and optical fiber light guides [89]. A POC device based on LIF microfluidics has the potential to decrease the time and quantity of reactants for analysis, along with multiplexing and portability [84].…”

An integrated device for fast and sensitive immunosuppressant detection

“…glass) or substrates (e.g. metal foil and silicon wafer), in particular with respect to microfluidic components, and their low mass production cost, which made them a good solution for the detection of very small radiation levels originating from low concentration fluorophore emission [34]. One of the ten photodiode series used in this system is depicted in Fig.…”

A Fluorescent Biosensors for Detection Vital Body Fluids’ Agents

“…Extensive settlement procedures are very often time-consuming and require the recruitment of specially trained personnel. Thus, the conversion concept and the design of microfluidic chips are the key factors for the practical application of the device [ 21 ].…”

“…Generally, the endogenous catecholamine concentration, which has been measured for patients without any diagnosed disorders, was approximately 150–800 ng/L for NE and 10–50 ng/L for EP and dopamine (DA) [ 21 ]. Their level can be measured in different biological fluids, such as plasma, saliva, urine, or blood serum [ 61 ].…”