Antenna integration with nanotechnology-based thick-film circuits for sensor applications

The attractive electronic properties of thin and thick films made of carbon nanotubes (CNTs) and graphene are increasingly being exploited for environmental and biological sensors. In particular, their sensitivity, selectivity, fast response time, ability to operate at room temperature, and their passive nature (no power consumption) provide competitive advantages of CNTs in sensor applications. However, their design as RF wireless sensors requires the integration of an antenna with the sensor element. In this paper, we present novel design of an aperture coupled antenna which is weakly coupled to an interdigitated capacitor (IDC) that serves the dual purpose of antenna impedance matching and the sensing function, the latter enabled by a thick film of CNTs deposited on the IDC surface. Simulations using CNT films of varying conductivity (or surface impedance) reveal that a strong antenna resonance can be produced. Furthermore, a study of the patch antenna radiation pattern with and without the CNT film shows weak coupling between the film and the antenna (loss of 0.5 dB or less relative to patch alone). Thus, the sensor film and geometry can be independently optimized without affecting radiation pattern.