[show abstract][hide abstract] ABSTRACT: A novel multiparametric biosensor system based on living cells will be presented. The biosensor system includes two biosensing techniques on a single device: resonant frequency measurements and electric cell-substrate impedance sensing (ECIS). The multiparametric sensor system is based on the innovative use of the upper electrode of a quartz crystal microbalance (QCM) resonator as working electrode for the ECIS technique. The QCM acoustic wave sensor consists of a thin AT-cut quartz substrate with two gold electrodes on opposite sides. For integration of the QCM with the ECIS technique a semicircular counter electrode was fabricated near the upper electrode on the same side of the quartz crystal. Bovine aortic endothelial live cells (BAECs) were successfully cultured on this hybrid biosensor. Finite element modeling of the bulk acoustic wave resonator using COMSOL simulations was performed. Simultaneous gravimetric and impedimetric measurements performed over a period of time on the same cell culture were conducted to validate the device's sensitivity. The time necessary for the BAEC cells to attach and form a compact monolayer on the biosensor was 35~45 minutes for 1.5 × 104 cells/cm2 BAECs; 60 minutes for 2.0 × 104 cells/cm2 BAECs; 70 minutes for 3.0 × 104 cells/cm2 BAECs; and 100 minutes for 5.0 × 104 cells/cm2 BAECs. It was demonstrated that this time is the same for both gravimetric and impedimetric measurements. This hybrid biosensor will be employed in the future for water toxicity detection.
[show abstract][hide abstract] ABSTRACT: In this paper we report on the electrical impedance spectroscopy characterization of endothelial cell lines (RFPEC). For electrical cell-substrate impedance sensing (ECIS) of the endothelial cells a commercially available eight-well cell culture impedance array (ECIS-8W1E) was used. The impedance measurements were recorded with cell culture medium (without cells) and with endothelial cell layer in the culture medium over a frequency range from 100 Hz to 100 kHz. The impedance measurements were compared to the equivalent circuit model. The impedance measurements of endothelia cells were also simulated using COMSOL Multiphysics™, a commercially available modeling package.
Circuits and Systems (APCCAS), 2010 IEEE Asia Pacific Conference on; 01/2011
[show abstract][hide abstract] ABSTRACT: The bimaterial cantilever beam is an important basic structure of microelectromechanical system thermal devices. The research described in this paper is a study of the deflection of the bimaterial cantilever beam operated in the air and irradiated with a laser beam at the free end. The bimaterial cantilever beam is a composite structure formed by layers of silicon nitride and gold. The temperature variations produce the deflection of the cantilever beam end due to different values of the thermal expansion coefficients of silicon nitride and gold. The deflection was experimentally measured in vacuum and atmospheric pressure when a laser beam was irradiated at the free end. A formula for the calculation of the deflection as a function of incident power applied at the free end of the cantilever beam operated in air was also demonstrated. The predicted values of the deflection calculated using this formula and the experimental values of the deflection were compared, and the results were in good agreement. A systematic investigation of the cantilever beam deflection in vacuum and atmospheric pressure as a function of the heat applied at the free end is important for chemical and biological applications.
The Review of scientific instruments 05/2010; 81(5):055104. · 1.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: Biosensors that employ live mammalian cells as sensing elements require precise information about the cell longevity. These biosensors could be stored in an incubator and used during the lifetime of the cells. This paper is a study of the longevity of bovine aortic endothelial cells (BAECs) that are used as sensorial component for cell-based biosensors. Different types of polydimethylsiloxane (PDMS) cell culturing chambers along with the culturing conditions required for BAECs to survive long term in lab on a chip systems are presented. The electric cell-substrate impedance (ECIS) technique was used to monitor cell viability over extended time periods. Media was automatically recirculated over the cells by a portable pump, in order to create the conditions required for testing the sensor in the field. It was demonstrated the BAECs could survive up to 37 days.