In-situ, Remote Query Chemical Sensors Based On Magnetoelastic Thick Films

University Of Kentucky Research Foundation, Lexington KY

Investigators

Abstract

This proposal seeks support for the development and application of a new remote query sensor technology based on changes in the resonant frequency of free-standing magnetoelastic thick films. The work builds upon, complements, and helps extend the chemical sensor oriented research the co-PI's are actively involved with. Magnetoelastic sensors are comprised of ribbon-shaped thick-films of magnetostrictive, magnetoelastic amorphous metallic glass [1]. In response to an ac magnetic field the sensors efficiently translate magnetic energy into elastic energy which, in turn, acts to mechanically deform the sensor. This mechanical deformation demonstrates a mechanical resonance the frequency of which is inversely proportional to the length of the sensor. It has recently been demonstrated [2] that the resonant frequency of a magnetoelastic sensor shifts in response to several different environmental parameters including pressure, temperature, viscosity, inter-facial molecular bond and, very importantly, when used in combination with a mass changing, chemically responsive layer [3] chemical analyte concentrations. Applications of magnetoelastic sensors to remote query chemical sensing has been demonstrated using a glucose responding polymer [4]. Changes in the resonant frequency of a magnetoelastic sensor have been measured in response to differential surface mass loadings below 0.9 ng/mm2. Three types of microporous thin-films were chosen for this study, providing a broad range of surface chemistries for controlling the adsorption and/or absorption of gas into the micropores. By controlling the pore size as well as the surface chemistry, we can tune the selectivity of the magnetoelastic sensor to a given compound in a mixture that may contain numerous different solute and solvent molecules.