Series quartz crystal sensor for remote bacteria population monitoring in raw milk via the Internet

Ku Shang Chang*, Hung Der Jang, Ching Fu Lee, Yuan Guey Lee, Chiun-Jye Yuan, Sheng Hsien Lee

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


A remote monitoring system based on a piezoelectric quartz crystal (SPQC) sensor was developed for the determination of the bacteria population in raw milk. The system employs the Windows XP server operating system, and its programs for data acquisition, display and transmission were developed using the LabVIEW 7.1 programming language. The circuit design consists of a circuit with a piezoelectric quartz crystal (SPQC) and a pair of electrodes. This system can provide dynamic data monitoring on a web-page via the Internet. Immersion of the electrodes in a cell culture with bacteria inoculums resulted in a change of frequency caused by the impedance change due to microbial metabolism and the adherence of bacteria on the surface of the electrodes. The calibration curve of detection times against density of bacteria showed a linear correlation coefficient (R2 = 0.9165) over the range of 70-106 CFU ml-1. The sensor could acquire sufficient data rapidly (within 4 h) and thus enabled real-time monitoring of bacteria growth via the Internet. This system has potential application in the detection of bacteria concentration of milk at dairy farms.

Original languageEnglish
Pages (from-to)1581-1590
Number of pages10
JournalBiosensors and Bioelectronics
Issue number8
StatePublished - 15 Feb 2006


  • Biosensor
  • Escherichia coli
  • Internet
  • Series piezoelectric quartz crystal


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