Quartz Resonator for Simultaneously Measuring Changes in the Mass and Electrical Resistance of a Polyaniline Film

Abstract

A novel quartz resonator was developed to measure, simultaneously, changes in the mass and electrical resistance of a polyaniline film during the absorption of water vapor. Interdigitated gold electrodes were vacuum-deposited on the sensing surfaces of the quartz crystals, and polyaniline films were drop-cast on the electrodes used to measure the changes in the electrical resistance. Two symmetric semicircular gold electrodes were deposited on the bottom surface of the quartz crystal. These electrodes were used to measure the changes in the mass of absorbed water based on the changes in the resonance frequency. The simultaneous measurements of mass and electrical resistance shed light on the interactions between the water vapor and the polyaniline film. The resonator was exposed to various organic gases, including ethanol, acetone, or chloroform, and each gas was found to produce characteristic changes in the normalized electrical resistance.

In situ measurement of photostability of CdSe/CdS/ZnO nanowires photoelectrode for photoelectrochemical water splitting

“…QCM is the widely used gravimetric sensors, which can measure accurately mass changes, due to their high sensitivity and durability [18][19][20]. The mass sensitivity of a QCM with a 5 MHz crystal is very high, typically 0.1 Hz/(ng −1 cm −2 ).…”

Laser-Induced Graphene on a Quartz Crystal Microbalance for Humidity Sensing

“…Generally, they require a tedious masking and thermal evaporation processes with vacuuming to deposit the electrodes on a quartz crystal. [7] This problem can be addressed by applying a laser process to the polymer-coated QCM to prepare electrodes and sensing materials in one step at room temperature. Laser-induced graphene (LIG) is a carbon nanomaterial that can be easily synthesized using a CO2 laser to convert polymer films.…”

“…However, this approach presents a limitation: QCMs and electrical sensors must work separately or the two electrodes can interfere with each other [3][4][5][6]. To solve this problem, several studies have attempted to change the structure of the QCM electrodes and integrate orthogonal sensor arrays [7,8]. These integrated systems have multiple sensing mechanisms from the QCM and additional sensor array, and therefore, change in specific manners depending on the target gas type.…”

“…To fabricate a QCM gas sensor able to incorporate additional electrodes, the sensing materials should be deposited sequentially on a quartz crystal. Generally, they require a tedious masking and thermal evaporation processes with vacuuming to deposit the electrodes on a quartz crystal [7]. This problem can be addressed by applying a laser process to the polymer-coated QCM to prepare electrodes and sensing materials in one step at room temperature.…”

Direct synthesis of Cu-BDC frameworks on a quartz crystal microresonator and their application to studies of n-hexane adsorption

“…[14][15][16] In contrast to the conventional methods, nanomechanical gravimetric sensors such as microcantilevers and quartz crystal microresonators (QCMs) are sensitive to changes in mass, especially on the sensor surface. 12,13,[17][18][19] Their resonance frequencies decrease with the increasing mass of the adsorbed gas molecules.…”