An embedded portable biosensor system for bacterial concentration detection

• Published in: Biosensors & bioelectronics 2010-11, Vol.26 (3), p.983-990
• Main Authors: Grossi, M., Lanzoni, M., Pompei, A., Lazzarini, R., Matteuzzi, D., Riccò, B.
• Format: Article
• Language: English
• Subjects: Bacteria; Bacterial count; Bacterial Load - instrumentation; Bioengineering; Biological and medical sciences; Biosensing Techniques - instrumentation; Biosensors; Biotechnology; Electric Impedance; Electromagnetism; Electronics; Embedded system; Engineering Sciences; Equipment Design; Food safety; Fundamental and applied biological sciences. Psychology; Impedance; Methods. Procedures. Technologies; Portable biosensor; Temperature; Various methods and equipments
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2010.08.039

Microbial screening is a primary concern for many products. Traditional techniques based on standard plate count (SPC) are accurate, but time consuming. Furthermore, they require a laboratory environment and qualified personnel. The impedance technique (IT) looking for changes in the electrical characteristics of the sample under test (SUT) induced by bacterial metabolism represents an interesting alternative to SPC since it is faster (3–12 h vs. 24–72 h for SPC) and can be easily implemented in automatic form. With this approach, the essential parameter is the time for bacteria concentration to reach a critical threshold value (about 10 7 cfu mL −1) capable of inducing significant variations in the SUT impedance, measured by applying a 100 mV peak-to-peak 200 Hz sinusoidal test signal at time intervals of 5 min. The results of this work show good correlation between data obtained with the SPC approach and with impedance measurements lasting only 3 h, in the case of highly contaminated samples (10 6 cfu mL −1). Furthermore, this work introduces a portable system for impedance measurements composed of an incubation chamber containing the SUT, a thermoregulation board to control the target temperature and an impedance measurement board. The mix of cheap electronics and fast detection time provides a useful tool for microbial screening in industrial and commercial environments.