| The objective of this research is to develop a point-of-care testing (POCT) infrastructure from a micro blood sampling system to a sample-to-answer immunoassay lab-on-a-chip, which is based on the full characterizations of microfluidic immunoassay performance on polymer microchannels, for intensive care of neonates and pediatrics in ICU. First, a new micro blood sampling system has been designed, fabricated, and characterized for providing micro-volume of blood to reduce iatrogenic blood loss from the catheterized neonates and pediatrics in ICU. In order to further reduce the blood loss during the sampling procedures, the system was designed for saving a discard blood, which is the initial volume of the sampled blood to be discarded as mixed with medication, to be returned to the patients. This can be done by having a closed structure that also decreases the risk of infection during the sampling procedures. In addition, the system was designed to have compatibility with the blood sampling procedures in the current clinical settings. As a result, the new micro blood sampling system can safely aspirate a micro volume of blood for the subsequent analysis in the lab-on-a-chip systems with minimal blood loss from the neonates and pediatrics in the ICU. Second, in order to perform immunoassay for the analysis of the micro volume of blood aspirated from the micro blood sampling system, a spiral microchannel on polymer substrates as a key component of the sample-to-answer immunoassay polymer lab-on-a-chip has been designed, fabricated, and successfully characterized for the microfluidic immunoassay. The spiral polymer microchannel was fabricated on polymer substrates using a computer numerical control (CNC)-milled master mold and a hot-embossing method. The performances of the microfluidic immunoassay for thyroid stimulating hormone (TSH) were characterized as an evaluation vehicle in terms of the crucial immunoassay parameters such as capture antibody and detection antibody concentrations, different capture antibody coating buffers, time for sample incubation, effect of polymer substrate materials, and different channel depths of the spiral polymer microchannels. The characterization results for the microfluidic immunoassay performances on the polymer microchannel can be very informative for other immunoassays to be designed on polymer microchannels. Third, based on the understanding obtained from the microfluidic immunoassay characterization results on polymer microchannels, a new sample-to-answer polymer lab-on-a-chip, which can perform a sandwich enzyme-linked immunosorbent assay (ELISA) with minimum user intervention through on-chip reservoirs for reagents and single-channel assay system, has been designed, developed and successfully characterized as a POCT cartridge for the detection of thyroid stimulating hormone (TSH). Users only need to drop a sample to the POCT cartridge to obtain test results within 30 minutes. The analyzed results of TSH showed a linear range up to 55 microIU/mL with the limit of detection (LOD) of 1.9 microIU/mL at the signal to noise ratio (SNR) of 3. The reagents stored in the on-chip reservoirs maintained their volume more than 97 % of the initial volume for 120 days of storage time while the detection antibody retained its activity above 98 % for 120 days. The sample-to-answer polymer lab-on-a-chip developed in this work using the mass-producible and low-cost polymer is well suited for the POCT of rapid in vitro diagnostics (IVD) of TSH. |
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