Monitoring of yeast cell concentration using a micromachined impedance sensor

Abstract

This paper describes the design, modeling and experimental characterization of a micromachined impedance sensor for on-line monitoring of the viable yeast cell concentration (biomass) in a miniaturized cell assay. Measurements in Saccharomyces cerevisiae cell culture show that the characteristic frequency describing the ␤-dispersion of S. cerevisiae cells is around 2.8 MHz. The permittivity change of the cell suspension was measured for the concentration range 0-9 g/l and depends linearly on the biomass concentration. In order to compensate the measurements for the electric properties of the background electrolyte, which increases the sensitivity and allows measurements in different media, the use of a three-electrode configuration in combination with a semi-permeable poly(2-hydroxyethyl methacrylate) (pHEMA) membrane was explored. Measurements show that the impedance of hydrated pHEMA varies with the background electrolyte conductivity only, and not with the concentration of cells, indicating that pHEMA is suitable for this purpose. The optimal pHEMA membrane thickness was determined using finite-element modelling and was found to be 1 m for the electrode configuration under study.

Review on Impedance Detection of Cellular Responses in Micro/Nano Environment

“…Typically, a pair of electrodes as an electrical transducer is utilized to measure the impedance change caused by the existence of the biological substances. Literature has demonstrated the use of the similar principle for the detection of various biological substances such as enzymes [23], antibodies and antigens [10,[24][25][26], DNA [27,28], and cells [17,[29][30][31][32][33]. This technique provides a non-invasive and label-free measurement, and is found practically useful for the detection of substances in miniaturized analytical devices like microfluidic systems.…”

Oral presentations

“…Haemophilus influenzae (Hi), Neisseria meningitidis (Nm), Group A Streptococcus (GAS), and Group B Streptococcus (GBS) were forwarded to reference laboratories in AK (2000AK ( -2006, N Can (2000N Can ( -2006, GN (2001-2006), Nor (2005-2006 and N Swe (2003)(2004)(2005) for confirmation and serotyping. Norway did not provide data for GAS and GBS.…”

“…Rates* of Invasive Disease,ICS Data, 2000-2006 Aboriginal peoples of AK and N Can have higher rates of invasive bacterial disease caused by Hi and GAS than non-aboriginals. Overall rates of Nm disease are higher in GN than AK, N Can, N Swe and Nor.…”

Disturbing-Free Determination of Yeast Concentration in DI Water and in Glucose Using Impedance Biochips

“…The plate count agar (PCA) technique and counting under microscope would be highly time consuming and it always involves human errors. Such disadvantages call for more adequate electrical analysis methods, e.g., microfluidic impedance cytometer [1][2][3][4] and impedance biochips, which have been used to count and discriminate yeast cells on the basis of their dielectric and electrical properties. The determination of the cell density with impedance biochips, on the contrary, is extremely fast and it prevents operator malfunctions.…”