A Novel Biosensor Based on Silver-Enhanced Self-Assembled Radio-Frequency Antennas

In this letter, 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. In the presence of the target analytes or pathogens, a silver-enhancement process self-assembles a chain of micromonopole antennas. As the size of the silver-enhanced particles grow, the chain of microantenna segments bridges 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 20 to 60 ng in this letter) can be detected based on the strength of the reflected RF signal received at a 915-MHz COTS RFID reader.