Capacitively Coupled Contactless Conductivity Detection (C4D) is a method for identifying ions and biomolecules in solutions separated by capillary electrophoresis. A C4D device operates by applying an AC voltage across two electrodes set up near to a capillary tube, allowing it to measure the electrical conductivity and permittivity of the substance inside the tube. This technique does not require direct contact with the fluid under observation, giving it several advantages over conventional conductivity detection devices. In this thesis our aim was to develop and optimize a sensitive C4D device able to operate at high frequencies of AC excitation voltage, allowing for identification of a wider range of ions and biomolecules. We studied and simulated transmission line characteristics, configuration of the excitation electrodes, and electrical shielding in efforts to increase the sensitivity of our devices.