Construction and development of a multifunctional measuring device for biomedical applications

Detta är en Master-uppsats från Umeå universitet/Institutionen för fysik

Författare: Tobias Nilsson; [2016]

Nyckelord: lab-on-chip; bio-sensors;

Sammanfattning: Lab-on-a-chip technology is a rapidly growing research area. Joining together several disciplines, such as physics, biology and several instances of nanotechnologies. The aim of this research is mainly to produce chips that can do the same types of measurements as large lab equipment and measurement systems, but at a fraction of the size and cost. In this work a multifunctional measuring device have been developed. It can measure optical absorbance and fluorescence while performing a range of potentiometric techniques; including chronoamperometry, linear- and cyclic voltammetry. From all these measurements it is possible to calculate particle concentrations in fluid samples. The aim is to bring simpler and cheaper point of care devices to the public. Without larger losses in accuracy and reliability of the medicinal test. To do this our device is intended to be used with lab-chip, which are capable of amplifying the signals while reducing the sample size. Lab-chips could be used in several areas but the ones being designed with this device are made for biomedical purposes, applying suitable nanostructures and reagents to measure the presence of biomarkers. With these techniques, medicinal diagnostics can be made a few minutes after samples have been collected from patients. Much quicker and more direct than sending the samples to a lab and waiting hours if not days for the results. The measuring device or lab-chip reader will use two different lab-chips in the future. One that is optimised for optical absorbance and the other for fluorescence. Both will work with electrochemical measurements, but at present only the absorbance chip have been available for testing and that without any signal enhancing techniques. Assessment of the reader's capabilities was made with solutions of gold nanoparticles, TMB (tetramethylbenzidine), iron dissolved in PBS (Phosphate-buffed saline) and with a film made of PPV (Poly para-phenylenevinylene). The first two were used to test absorbance; while the iron and PBS have been used to test electrochemical system; and the PPV was coated on a glass substrate and used to test fluorescence. During the optical absorption test, it was found that the reader can distinguish between different concentrations of the various solutions. The results are promising and further removal of signal drifts will improve signals considerably. Fluorescence can be induced and measured with the device. This part of the system is, however, untested in general and future work will show if it is sufficient. The iron solution was tested with three different methods. chronopotentiometry, linear sweep voltammetry and cyclic voltammetry. It was however found that our measurements were distorted in comparison with the expected voltammogram for iron in PBS. Additional peaks were found in the voltammogram and it is believed that these are a result of oxidation of the electrodes on the lab-chip.

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