Capacitively-coupled differential position detection in the development of a high-sensitivity torsion balance

We report on the development of a high-sensitivity torsion balance using a capacitively-coupled Wheatstone Bridge. The torsion balance will be employed to measure the Casimir Force, with a particular emphasis on the surface patch effects that are ubiquitous on metallic surfaces.~We will show that these effects also play a significant role~in another class of experiments involving quantum-point contacts between two metal wires.