Sensing by growing antennas: A novel approach for designing passive RFID based biosensors

In this paper, we show that a silver-enhancement technique can be used to self-assemble a radio-frequency (RF) antenna which then can be used for designing a radio-frequency identification (RFID) based biosensor. Using the proposed biosensor, the concentration of target analytes or pathogens can be remotely interrogated in a concealed, packaged or in a bio-hazardous environment, where direct measurement is considered to be impractical. The presence of the target analytes or pathogens, self-powers a silver-enhancement process which then assembles a chain of micro-monopole antennas. As the size of the silver-enhanced particles grows, the chain of micro-antenna segments bridge together to complete a dipole structure that reflects impinging RF signals at a desired frequency. We validate the proof-of-concept for IgG detection and demonstrate that different concentrations of rabbit IgG (ranging from 20ng to 60ng in this paper) can be detected based on the strength of the reflected RF signal received at a 915MHz COTS RFID reader.