A turbine fuel pump includes: a casing for casing an electric motor; a pump housing disposed at the casing, and an impeller rotatably disposed in the pump housing. Chambers nest within one another to form a stack of chambers for transport or storage. Next, a first resonant response of the resonant test structure is obtained when the resonant test structure is electromagnetically coupled to a reference sample, the reference sample having a known composition. Features are etched into the etch layer through the photoresist features and the photoresist mask is removed. The assembly further includes a coupler engaging the bracket.