In this lecture, we start off with a light review of the nanopore sequencing method which is based upon having a carefully bioengineered pore that can induce different changes in charge blockages as different base pairs go through the pore. Then, the coulter counter which is a small aperture separating two chambers filled with conductive electrodes is seen. Fluid containing the cells is drawn through the channel and as the particle occupies the channel, resistance increase and the change in it is measured through a fixed voltage. The size of the current change is proportional to the size of the particle. Example data from a coulter counter is then seen. Cell adhesion is the coupling between cell and surface which is a fundamental aspect to many important processes. The CellKey uses this method and measures the changes in impedance that occur in response to stimulation by supplying a constant voltage, that at low frequencies flows both around and between cells and at high frequencies through cells. The things that contribute to the impedance measurements are the changes in cell-substrate adherence, changes in cell shape and volume, and changes in cell-cell interactions. The combined data from lots of cells, not individuals is measured. Example data of this method is then shown. The advantages and disadvantages of the impedance-based detection methods is then discussed. Last, an overview of the next lecture about fluorescence based detection methods is seen with an introduction to energy levels and photons.

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

Researchers should cite this work as follows:

• Brian Cunningham (2013), "[Illinois] ECE 416 Impedance Based Sensors II," https://nanohub.org/resources/17356.

  BibTex | EndNote

1. biosensors/sensing
2. course lecture
3. Illinois
4. NanoBio Node at Illinois
5. sensors/sensing