Selective detection of chemical species in liquids and gases using radio-frequency identification (RFID) sensors

We demonstrate selective and sensitive chemical sensing based on battery-free passive radio frequency identification (RFID) sensors. Developed sensors are illustrated in sensing of ions and organic solvents in water and toxic vapors in air. These sensors are immune to variable ambient conditions, including air bubbles (in water sensing) and uncontrolled levels of relative humidity (in gas sensing).