Chameleons are hypothetical scalar particles and are candidate components of Dark Energy. The eective mass of chameleons depends on the local matter-energy density, enabling them to evade constraints from "fth force" experiments and resulting in the property that they can reect o surfaces at grazing angles. These particles are ex- pected to be produced in the Sun, with escaping chameleon's energies in the order of 102 eV. Chameleons reecting o a surface would exert a tiny force which could be detected using sensitive membrane-based detectors. Existing X-ray telescopes, such as the ABRIXAS telescope installed at CAST (CERN Axion Solar Telescope) may be used to increase the detection probability by focusing the solar chameleon ux onto such a membrane detector. KWISP (Kinetic WISP detector) is a sensitive optomechanical force sensor currently in use at CAST; its working principles and operation are described in this thesis. In order to enable chameleon detection a special "chameleon" chopper is placed in front of KWISP in order to modulate the incoming chameleon stream. An optical homo- dyne detection scheme is used to measure the small membrane displacements. Data acquisition has been implemented on a single board computer and custom software has been written that allows for continuous reliable data acquisition and transfer at suitable sample rates. The sensitivity achieved was 3:2 10􀀀10 N= p Hz.