[Illinois] ECE 416 Impedance Based Sensors I

By Brian Cunningham

University of Illinois at Urbana-Champaign

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           In this lecture, we were introduced to the concept of a new sensor called the impedance-based Biosensor. Biomolecules are originally charged and therefore there is a need to determine the charge of the molecule before using it on a sensor. Isoelectric Points, the pH at which a protein has a net "0" Charge, can now be looked up and used to determine whether the protein in mind is positively or negatively charged. The charge of the biomolecule when attached to a transistor can impede the Biosensor and this impedance can be used to detect these molecules. The transistor is two electrodes (a source and a drain) that conducts a channel between them. A protein is "put" on top of the transistor and because negative charges repel, the proteins electrons will displace the electrons from the conductor and the make the conductor less conductive. Silicon Nanowire Transistor Biosensors will use this method in order to detect the molecules. However, the charges of the surrounding environment will cause a change in the charge,not the biomolecule, and impede the electrons. The Debye Length enables the sensor to ignore the changes within a bulk solution, but will block some of the results that the biomolecule is expected to produced. Nanopore Based Detection is then discussed in regard to DNA Sequencing. This method uses the protein to move charges and big biomolecules will block the channel. Through the current differences in the engineered pores, the different DNA base pairs can be seen. Mutations are made to the pore to alter the structure of the most narrow part of the barrel of the protein. This means that this sensor can read the sequence of DNA as it flows through the pore.


My research group is focused on the application of sub-wavelength optical phenomena and fabrication methods to the development of novel devices and instrumentation for the life sciences. The group is highly interdisciplinary, with expertise in the areas of microfabrication, nanotechnology, computer simulation, instrumentation, molecular biology, and cell biology. In particular, we are working on biosensors based upon photonic crystal concepts that can either be built from low-cost flexible plastic materials, or integrated with semiconductor-based active devices, such as light sources and photodetectors, for high performance integrated detection systems.

Using a combination of micrometer-scale and nanometer-scale fabrication tools, we are devising novel methods and materials for producing electro-optic devices with nanometer-scale features that can be scaled for low-cost manufacturing. Many of our techniques are geared for compatibility with flexible plastic materials, leading to applications such as low cost disposable sensors, wearable sensors, flexible electronics, and flexible displays. Because our structures manipulate light at a scale that is smaller than an optical wavelength, we rely on computer simulation tools such as Rigorous Coupled Wave Analysis (RCWA) and Finite Difference Time Doman (FDTD) to model, design, and understand optical phenomena within photonic crystals and related devices.

In addition to fabricating devices, our group is also focused on the design, prototyping, and testing of biosensor instrumentation for high sensitivity, portability, and resolution. Advanced instruments enable high resolution imaging of biochemical and cellular interactions with the ability to monitor images of biochemical interactions as a function of time. Using the sensors and instrumentation, we are exploring new applications for optical biosensor technology including protein microarrays, biosensor/mass spectrometry systems, and microfluidics-based assays using nanoliter quantities of reagents. The methods and systems developed in the laboratory are applied in the fields of life science research, drug discovery, diagnostic testing, and environmental monitoring. -From Professor Cunningham's Faculty Profile

Cite this work

Researchers should cite this work as follows:

  • Brian Cunningham (2013), "[Illinois] ECE 416 Impedance Based Sensors I," http://nanohub.org/resources/17355.

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University of Illinois, Urbana-Champaign, IL


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