Development of nanomaterial based sensors for biomedical applications

Fabrice Fomo Fondjo

Due to the mechanical and electrical versatility of nanoscale forms, various nanomaterials have rapidly established themselves as promising electronic materials for various biosensing applications ranging from the traditional electrochemical methods to the more recent wearable biosensors. These nanomaterial-based biosensors have demonstrated enhanced sensitivity, selectivity, and minimal interferences from biological matrices. However, one of the challenges for practical implementation of nanomaterial-based sensors is their poor reproducibility due to lack of control for arrangement of nanomaterials on sensor. Thus, highly controlled manipulation of nanomaterials is still a major challenge. To overcome this challenge, this thesis describes two simple ways to apply nanomaterials for development of biosensors. The first part of this thesis presents the fabrication of hybrid nanocomposite membranes for wearable biosensing applications, which can mitigate the mechanical mismatch between the conventional rigid electronics and the soft human body. The fabricated hybrid membrane was composed of zero-dimensional carbon black (CB) and one-dimensional multi-walled carbon nanotubes (MWCNTs) and silver nanowires (AgNWs) in a polydimethylsiloxane (PDMS) matrix. To achieve a homogeneous dispersion, these nanomaterials were mechanically mixed in PDMS under various mixing conditions. A hybrid nanocomposite membrane was then prepared with various dimensions by replica molding process. These hybrid nanocomposite membranes were laminated on the skin and demonstrated to enable highly sensitive recording of electromyograms. The second part is centered on the development of a label-free amperometric biosensor using single-walled carbon nanotubes (SWCNTs) for the rapid and inexpensive screening of infectious disease. SWCNTs plays the role of a transducer in biological antigen/antibody reaction for the electrical signal. The electrode patterns were produced by the stamping of silver ink on a PET film. To achieve a uniform coating of SWCNTs on a silver electrode, polyethylenimine (PEI) was employed as an adhesive layer. To evaluate the sensor performance, Mycobacterium tuberculosis antigen, one of the world deadliest diseases, airborne and mainly targeting the lungs, was used as a model analyte.

Development of nanomaterial based sensors for biomedical applications

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