An Embedded Portable System for Bacterial Concentration Detection (original) (raw)
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An embedded portable biosensor system for bacterial concentration detection
Biosensors and Bioelectronics, 2010
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.
Journal of Electrical Engineering and Electronic Technology, 2014
such as food quality control and environmental monitoring. High values of bacterial concentration and/or the presence of pathogenic bacterial strains can seriously endanger human health, thus microbial concentration must be regularly screened to meet national and international regulations. Bacterial concentration is measured by Standard Plate Count technique, a reliable and accurate method that is however characterized by long time response (24-72 hours) and the need to be performed in a laboratory environment by skilled personnel. Our research group has recently developed an embedded portable biosensor system that is competitive with the standard technique in terms of response time and can be easily used for in-situ measurements by users with no microbiology knowledge. In this paper we discuss an algorithm for the transformation of the biosensor measured data that proves to be accurate and easy to be implemented. The algorithm is based on the calculation of the first and second time derivatives of the measured electrical parameters and the results show good correlation (R 2 = 0.829) between the bacterial concentration estimated with the biosensor and that measured by the standard technique.
2017 7th IEEE International Workshop on Advances in Sensors and Interfaces (IWASI), 2017
The detection of bacterial concentration is important in different fields since high microbial contamination or the presence of particular pathogens can seriously endanger human health. The reference technique to measure bacterial concentration is Standard Plate Count (SPC) that, however, has long response times (24 to 72 hours) and is not suitable for automatic implementation. This paper presents a portable embedded system for bacterial concentration measurement based on Impedance Microbiology that is suitable for in-situ measurements and does not require trained personnel. The system has been tested with samples inoculated with different concentrations of Escherichia coli and its response correlates very well (R 2 = 0.9185) with results from SPC.
Impedance microbiology—a rapid change for microbiologists
Journal of Applied Microbiology, 1996
1. Introduction, 233 1.1 Direct impedance, 234 1.2 Indirect impedance, 234 2. Applications in the food industry 2.1 Total viable counts, 235 2.2 Salmonella detection, 235 2.3 Listeria detection, 236 2.4 Coliform testing, 236 2.5 Clostridia, 237 2.6 Yeast, 237 2.7 Lactic acid bacteria and the dairy industry, 237 2.8 Predictive microbial growth modelling, 238 3. Non-food related applications 3.1 Antibiotic resistance, 238 3.2 Biocide efficacy testing and microbial biofilms, 239 3.3 Detection of plant pathogens, 240 3.4 DNA damage evaluation, 240 3.5 Impedance-based enzyme assays,
Detection of Coliforms Concentration in Water Samples by Portable Impedance-based Biosensor System
Proceedings of ECOMONDO, 2010
Il controllo del contenuto microbico delle acque assume un ruolo particolarmente importante all'interno dei processi di monitoraggio ambientale. L'analisi della concentrazione batterica è normalmente realizzata tramite conta in piastra, una tecnica affidabile ma caratterizzata da lunghi tempi di risposta (24 -72 ore) e che necessita di operazioni abbastanza complesse da svolgersi presso un laboratorio microbiologico da parte di personale qualificato. Il presente lavoro presenta un sistema portatile a biosensore per il monitoraggio della concentrazione batterica in campioni liquidi e semiliquidi che unisce tempi rapidi di risposta e semplicità di utilizzo. Tale dispositivo determina la concentrazione batterica del campione analizzando le caratteristiche elettriche del mezzo. Il biosensore è stato utilizzato con successo per la stima della concentrazione di coliformi in campioni di acqua di diversa provenienza. I risultati mostrano la possibilità di rilevare cariche batteriche elevate (> 10 5 cfu/ml) in tempi relativamente brevi (3 -4 ore) e una buona correlazione con i dati ottenuti dalla conta in piastra.
Low-cost digital impedance meter for the detection of micro-organisms
Journal of Biomedical Engineering, 1988
The digital impedance meter is a microprocessor-based instrument able to detect, quantify and identify micro-organisms. The equipment makes use of the bipolar technique of measuring the impedance modulus of six cells containing inoculated culture broth. It performs temperature compensation automatically. Growth curves are stored in memory as time course events and can be displayed on any suitable device.
A portable sensor system for bacterial concentration monitoring in metalworking fluids
Journal of Sensors and Sensor Systems, 2018
The detection of bacterial concentrations in metalworking fluids (MWFs), oil-in-water emulsions used in the cutting industries for cooling and lubrication, is important in order to extend the product life-cycle and plan its disposal according to regulations and legislations. The standard method of measuring culturable bacterial concentration is the plate count technique (PCT) that, however, has long response times and is not suitable for automatic implementation outside a laboratory. In this paper a portable sensor system that measures the bacterial concentration in liquid and semi-liquid media exploiting impedance microbiology is presented and tested for the application of MWF microbial monitoring. A set of MWF samples, taken from metalworking plants, have been tested and good agreement has been found between the system response and that of the PCT. The proposed system allows automated bacterial concentration measurements with shorter response times than the PCT (4 to 24 h vs. 24 to 72 h) and is suitable for in-the-field MWF monitoring.
Procedia Chemistry, 2009
Electrochemical impedance spectroscopy (EIS) is applied to detect pathogenic E. coli O157:H7 bacteria via a label free immunoassay-based detection method. Polyclonal anti-E.coli antibodies (PAb) are immobilized onto gold electrodes following two different strategies, via chemical bond formation between antibody amino groups and a carboxylic acid containing selfassembled molecular monolayer (SAM) and alternatively by linking a biotinylated anti-E. coli to Neutravidin on a mixed-SAM. Impedance spectra for sensors of both designs for increasing concentrations of E. coli are recorded in phosphate buffered saline (PBS). The Nyquist plots can be modeled with a Randle equivalent circuit, identifying the charge transfer resistance R CT as the relevant concentration dependent parameter. Sensors fabricated from both designs are able to detect very low concentration of E. coli with limits of detection as low as 10-100 cfu/ml. The influence of the different immobilization protocols on the sensor performance is evaluated in terms of sensitivity, dynamic range and resistance against nonspecific absorption.
A portable biosensor system for bacterial concentration measurements in cow's raw milk
2011 4th IEEE International Workshop on Advances in Sensors and Interfaces (IWASI), 2011
Bacterial detection is of primary importance in many fields, such as food and environmental monitoring. Measurements of bacterial concentration are traditionally carried out by means of the Standard Plate Count technique, a reliable method for microbial screening that, however, features long response time and is carried out by qualified personnel in microbiology laboratories. The impedance technique for bacterial concentration detection represents a method very competitive with Standard Plate Count in terms of response time (3-12 hours vs. 24-72 hours) as well as for the possibility to be realized in automatic form. This paper presents an embedded portable biosensor system for the measurement of bacterial concentration in cow's raw milk. The possibility to perform measurements "on the field", hence without the need to ship samples to distant laboratories, and to transmit the data on wireless communication systems or on the Internet represents a substantial advantage in terms of time and cost, thus making the presented system an important tool for in-situ bacterial screening.