w.Development of bioelectronics for inertial sensing applications

Abstract

ABSTRACT: Inertial navigation systems (INS) are employed for the accurate navigation of military and civil vehicles. Modern non-conventional INS technologies incorporate the use of microelectromechanical systems (MEMS) such as microgyrometers and microaccelerometers to act as the sensing component. The development of bioelectronics has been integrated with microaccelerometer technology to develop a novel sensitive sensing system. The bioelectronic element consisting of a metallised DNA nanowire anchored between a sensing gap to allow the measurement of acceleration. The approach of bottom up fabrication (i.e. building up from constituent parts) has been undertaken for the development of bioelectronics allowing the assembly of novel MEMS microaccelerometers. The use of surface gold thiol (-SH) chemistry has been performed to allow highly specific deposition of deoxyribonucleic acid (DNA) molecules on sensing surfaces. The placement of λ-DNA immobilisation and hybridisation has been analysed in real time by utilising techniques such as surface plasmon resonance (SPR) allowing the suitability of the protocols to be scrutinised for DNA nanowire formation. The design and fabrication of MEMS microaccelerometers was undertaken with exact specifications to allow the immobilisation and subsequent DNA nanowire assembly for the bioelectronic sensing component to be realised. The microaccelerometers were characterised by scanning electron microscopy (SEM) and optical profilometry to determine the suitability for the application. The use of self assembled monolayers (SAMs) was exploited to immobilise DNA specifically on gold sensing electrodes. Sequence specific complementary DNA hybridisation was employed giving the ability to further position the nanowires between gold sensing electrodes. The positioning being achieved using dielectrophoretic (DEP) methods to stretch and align immobilised DNA in the required direction and orientation. Further the DNA was subjected to metallisation to give electrical functionality that allows it to be used as the sensing element. The intercalation of metals such as zinc onto DNA templates was performed and monitored using spectrophotometric methods to allow a future assessment of the electrical properties. The research aim being to develop robust hybridisation protocols for the controlled selective placement and subsequent metallisation of DNA to allow the integration of bioelectronics into novel nanoscale microaccelerometer systems.