An essay on the development of an interferometer biosensor integrated with an electro-kinetic technique

Labella, Elisabetta (2023). An essay on the development of an interferometer biosensor integrated with an electro-kinetic technique. University of Birmingham. Ph.D.

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Abstract

A novel optical biosensor is herein presented for label-free analytes detection combining a Young’s interferometer and electrophoresis technique employing agarose gel. The interferometer consists of a Fresnel Biprism as beam splitter, a microfluidic chip and the output of this device, an interference pattern, is detected by a CMOS camera. The electric field focuses and actively drives the analytes through a hydrogel-filled channel to the analysis region. As the analytes move, the interference pattern immediately presents a circumscribed shift as a result of the refractive index (RI) modification of the transparent hydrogel. The shift is proportional to the analytes’ concentration. In this thesis we describe the theory behind the operation of the instrument and its characterization, highlighting the results about the RI change detection and the correlation between the analytes presence inside the hydrogel and the shift in the interferometer pattern. Finally, to prove the selectivity of our biosensor, the gel has been functionalised with Biotin molecules, which were able to actively attach Streptavidin molecules from a mixed solution. The Streptavidin-Biotin system has allowed us to prove the selectivity of the sensor. The PhD thesis wants to give a full description of the development of a new label free optical biosensor in its initial stage, by describing the challenges met, and the description of the results, which testify the proof-of-concept of our novel optical sensor for the Streptavidin-Biotin system.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):