Acoustic wave immunosensing of Escherichia coli in water

This paper reports an experimental study of E. coli sensing based on surface-skimming-bulk-wave delay line device fabricated on ST-cut quartz. The sensor configuration consisted of an 87.7 MHz oscillator with the delay line as control element in its feedback loop. The antigen-antibody immunochemical reaction was employed on the acoustic wave device surface to generate mass loading and frequency shift. The sensor output was monitored by an RF spectrum analyzer. Highly specific sensing is demonstrated for E. coli cells up to 0.4 cells/μl in water. The methodology offers possibility for developing highly sensitive and fast E. coli sensors for testing of water potability.