ChBE Seminar - Multianalyte Electrochemical Sensors on a Monolith Electrode and Electrochemical Devices

The Chemical and Biological Engineering Department will be hosting a seminar featuring Ravi Saraf, Distinguished Professor of the University of Nebraska-Lincoln who will be discussing Multianalyte Electrochemical Sensors on a Monolith Electrode and Electrochemical Devices.

Abstract:

Electrochemical sensors are arguably the most successful chemical sensing devices primarily because of their high sensitivity at low cost. With a worldwide market of $1.7B, the glucometer is perhaps the most successful commercial chemical/biochemical sensor in history. The key advantage of electrochemical devices is the active signal due to a reaction allowing specific recognition of the chemical with a low incidence of false positives. In this talk, I will describe two platforms, each addressing a fundamental limitation of current electrochemical devices. These platforms significantly enhance the capability of electrochemical sensing.

The first limitation is that only one redox reaction per electrode is possible to detect. We have developed an opto-electrochemical method, called Scanning Electrometer for Electrical Double-layer (SEED), to quantitatively detect multiple, individual redox reactions on a monolith electrode. By scanning a laser beam, local redox current density distribution can be quantitatively mapped to detect multiple analytes on a 1 cm2 size electrode. SEED is responsive to (redox) reactions of 0.1 atto-mole of molecules.

In the second example, I will address the diffusion limitation of redox reactions on the electrode. The sensitivity and speed in a electrode can be significantly enhanced by orders of magnitude by reducing the electrode size. At small electrode size, i.e., ultra-micro electrode, the redox current is not limited by the rate of diffusion of the ions. A metal nanoparticle is the ultimate size-scale; however, the ensembles of particles have to be far apart to avoid inter-particle interference. As a result, each nanoparticle is interconnected individually by an underlying electrode that makes the fabrication challenging. We developed a special architecture of dense nanoparticle arrays that is electrically conducting and exhibits the nanoelectrode effect.

Application to chemical and biochemical sensing, cell biology, and genomics will be discussed for both platforms.

Short Biography

After receiving a B.S. from the Indian Institute of Technology, Kanpur, in Chemical Engineering, and a Ph.D. in Polymer Science at the University of Massachusetts, Amherst, Ravi joined IBM's T.J. Watson Research Center at Yorktown Heights in 1986.

He left Yorktown in 1999 to join the Chemical Engineering faculty at Virginia Tech. Since 2004, he has been a faculty member at the University of Nebraska-Lincoln.

Ravi's research interests are in material science, device physics, nanoscale phenomenon, and electrochemical processes. His current research group is focused on probing single cell electronic processes, opto-electrochemistry, nanoparticle-based mesoscale systems, and (recently) scanning probe microscopy in water.
Ravi has over 50 patents and 100 peer-reviewed publications. His research over the years has been funded by the DoD (ONR and DARPA), NIH, DoE (BES), and NSF.

His research has been described in the popular science press, including Scientific American, Science (perspective, pod cast), Nature News, Science News, C & E News, MRS Bulletin, Discovery (Top 100 Inventions and Discoveries in 2006), and NPR (All Things Considered) and the BBC (Interview).