Graphene Oxide-Coated Quartz Crystal Microbalance for Bioparticle Detection (A Case Study for Bacillus sp.)

Bioparticle concentration can be measured using many techniques, such as mass spectroscopy, light scattering, and fluorescent tracking. Due to some instrument limitations, high cost, low sensitivity-selectivity level, and performance development needs, there is a need to develop a new sensing technique with higher performance. This study used quartz crystal microbalance (QCM) and graphene oxide (GO) as the selective coating materials. For this purpose, two different sensors were tested: uncoated QCM and GO-coated QCM. The sensor performances were tested inside an exposure chamber by exposing the sensors to different bacteria samples: B. pasteurii, B. sphaericus, and B. cereus. The sensor’s frequency shift was counted using a frequency counter, while the sample concentration was measured using a Digital Dust Monitor. The results show that the sensors work well in detecting Bacillus sp. samples with sensitivities of 0.24 to 0.35 Hz.µg^-1. The developed sensors have a response time of <96 s, with a linearity of 95%. The best response is obtained from the coated QCM using B. pasteurii. The coated QCM performs better than the uncoated QCM, indicated by better linearity, response time, and sensitivity.