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Bioanalysis through Patterning Low-Cost Substrates
thesisposted on 14.02.2017, 01:41 by Tian, Junfei
The health and well-being of the human population in the developing world has become an important global issue which attracts lots of attention from many governments in the developed world. Intensive research efforts have been made by the developed countries to address human health in developing countries. Some major diseases, such as malaria, HIV/AIDS, tuberculosis, etc. threaten the health and the productivity of the human population in developing countries, severely restricting the development of those countries. For some diseases, effective clinical treatments are now available and can be delivered to patients in those countries. However, the lack of robust and low-cost screening technologies still prevents the screening of those diseases among the large human population in developing countries. To overcome these problems, cheap materials such as paper and thread are utilized to fabricate low-cost microfluidic devices, bioactive paper and bioactive thread. It is feasible to use these cheap platforms to provide affordable healthcare and environmental monitoring in developing countries. These novel applications strongly drive the continuous development of low-cost diagnostics. The work in this thesis focuses on both novel fabrication concepts and detection mechanism designs to improve low-cost diagnostics by using simple patterning methods. Throughout this work, printing is used as a versatile and cost-effective approach for fabricating low-cost and simple diagnostic devices. Printing technologies are exploited in three ways. Firstly, printing is a simple fabrication method. With the necessary modifications, printing processes can create patterns of a variety of physical and chemical properties on a substrate to form a testing device. Secondly, printing can be used as a convenient delivery method for material delivery and transfer. Samples and detection reagents can be delivery to the desired position of the device to form the sensor. Thirdly, printing is a simple analytical method. Based on different contact printing mechanisms, printing can be employed to either transfer bio-inks or bio-effects onto bioactive paper. In one print, different kinds of biochemical reactions are triggered, which turn bioactive reagents into visible patterns appearing on a paper substrate at the same time. The user friendliness of a sensor critically determines the performance of the sensor under field conditions. This thesis also presents a novel concept for paper-based diagnostics, aiming to increase the clarity of assay results reported by the paper device to the user. This work, for the first time, designs a paper-based blood typing device that reports patient’s blood type in written text, enabling non-professional users to understand the testing results. This work further addresses a practical issue related to the sensor fabrication process. Work in this thesis proposes a new method of increasing the hydrophilicity of bioactive paper using plasma treatment while retaining the bioactivity of the paper. New concepts presented in this thesis further demonstrate the huge promise of low-cost and bioactive diagnostics in improving world health. Low-cost sensors enable a range of biological and environmental tests to be performed for purposes of health care, disease screening and environmental monitoring.