An analytical device including a sensor, an analytical circuit, and a power source. The power source includes an optical coupler formed of a light source and a photovoltaic cell for producing an electromotive force in response to light from the light source. The optical coupler is configured to provide the electromotive force to the analytical circuit. The power source may be configured for separation between the power supply and the resulting electromotive force supplied to the analytical circuit. Various aspects of the invention are directed to providing a power source for one or more components of an electrochemical detector. A method of providing power to an analytical instrument is also disclosed.