A sensor utilizing a non-leachable or diffusible redox mediator is described. In one aspect, the receiver includes a low noise amplifier that is capable of being enabled in a relatively quick fashion so as to amplify an incoming signal when needed, and then being disabled to set the LNA in a low power consumption mode. The transverse beams extend underneath the central tunnel and can be fastened with a free end in each case to the vehicle body by connecting devices. In this embodiment, the vacuum integrity of the chamber is not compromised during the cleaning of the electrostatic chuck.