Quartz Crystal Microbalance-Tag Apparatus for Wireless Mass Sensing Applications

We report a near-field communication (NFC)-enabled quartz crystal microbalance (QCM)-tag instrumentation suitable for wireless mass loading sensing applications. The proposed instrumentation utilizes a low-power microcontroller-based Pierce oscillator frequency counter system to measure series resonance frequency <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$(f_{0})$</tex-math></inline-formula> of the QCM over a time period. The system was able to record the change in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$f_{0}\,(\Delta f)$</tex-math></inline-formula> caused by mass loading to the NFC's electrically erasable programmable read-only memory. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$f_{0}$</tex-math></inline-formula> measured using the proposed system was then validated against impedance analyzer measurement, and the maximum error was measured to be 0.0004%. An Android application was then developed to read log <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$f_{0}$</tex-math></inline-formula> using a smartphone. Further, we demonstrated wireless measurement of the mass loading rate of a dc sputtering system, a well-known vacuum deposition technique adopted in semiconductor process industries. Accordingly, the proposed system is an inexpensive plug-and-play solution for real-time wireless in-situ measurement of mass loading changes in sealed chambers or hazardous environments where manual measurement or wired measurement is difficult.