Conventional detection of pathogens is a costly and tedious laboratory-based task that requires qualified and skilled professionals. Advancements in micro and nanotechnology have resulted in inexpensive biochemical sensors that can detect chemicals and biomarkers in low concentrations in near real time. In this project, we take one step further and propose three-dimensional (3D) biomimetic biosensors for food safety applications that mimic the porous medium of fresh produce. The 3D sensing platform can detect the presence of pathogens on the surface of the biomimetic structure, monitor their movement inside the medium (internalization), and also identify the potential formation of biofilm. The sensors use capacitive/impedance measurement for detection and have 3-dimensional structures made of a stack of electrodes. Different electrode structures including interdigitated and a parallel plate formation are used to determine how the microorganisms move inside a porous medium. This sensing platform provides a real-time, noninvasive, label-free and rapid detection technique to quantify pathogens’ presence on and inside fresh produce. Electrochemical impedance spectroscopy (EIS) technique is used for both interdigitated and 3D capacitive sensors for detection in aqueous solution and suspension. Sensors with the different number of sensing electrodes were fabricated on a silicon substrate using surface micromachining fabrication technology. An equivalent circuit of capacitive and resistive elements was developed to model the behavior of the combination of sensor and aqueous solution. This circuit can be used to associate the solution concentration to change in capacitive and resistive values for detection.
Experimental data and finite element simulation (ANSYS® APDL) of interdigitated and 3D biosensors were used to verify the system’s equivalent model and the relation between solution concentration and each electrical element (capacitance or resistance) of the system is determined. Moreover, di-(2-ethylhexyl) phthalate (DEHP) was used as the target chemical for detection and different concentrations were tested. The experimental results show the high sensitivity of the sensor to concentration change even at the extremely low concentration of 0.02 ppm. The proposed sensor not only can be used for chemical detection but can also be used for the detection of pathogens in aqueous suspension.
|Commitee:||Celik, Serdar, Gu, Keqin, shavezipur, Kamran|
|School:||Southern Illinois University at Edwardsville|
|School Location:||United States -- Illinois|
|Source:||MAI 58/04M(E), Masters Abstracts International|
|Subjects:||Bioengineering, Fluid mechanics, Engineering|
|Keywords:||Electrochemical impedance spectroscopy, Food safety, Food-borne pathogens, MEMS biosensors, MEMS chemical sensors, Three dimensional interdigitated sensor|
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