We study the properties of nanoscopic wires, particles, and films prepared by electrodeposition. Our objective is to understand how these nanomaterials behave in devices such as chemical sensors, biosensors, thermocouples, thermoelectric generators, photodetectors, and transistors. Our research is funded by the following agencies and entities:
Projects of current interest are the following:
Chemical Sensing. The key attribute of nanowires in chemical sensing is their tremendous surface area: volume ratio. In our gas sensing experiments, one surprise has been that the chemisorption of gas molecules to the metal surface is sufficient to generate a significant, measurable change in the wire resistance, enabling the detection of some gases at concentrations in the ppm range. Chemical sensors designed for the detection of solution-phase analytes, and operating on a completely different principle, are also under development.
Project Leader: Vivian Chen.
Energy storage. The high surface area : volume ratio of nanowires makes them attractive candidates for electrodes in batteries and supercapacitors. The key fundamental question is: What limits the performance of these materials? We are focusing attention on MnO2 which is a hybrid energy storage material that is capable of storing charge capacitively and Faradaically, as a change in the redox state of the Mn centers. The challenge is to prepare MnO2 nanomaterials that charge and discharge rapidly while also producing the highest possible energy density.
Project Leaders: Gaurav Jha and Josh Ziegler.
Photodetectors and photon emitters. A sensitive, fast photodetector based upon a photoconductive semiconductor nanowire remains an elusive goal. You can have one or the other: A fast device (Ás range) that is insensitive (Gain < 1.0), or a slow device (>1s range) that is ultrasensitive (Gain > 104). We need to understand more about carrier transport through grain boundaries in polycrystalline nanowires, about electrical contacts, and other issues before we will know whether this connundrum has a fundamental science solution.
Project Leaders: Shaopeng Qiao.
Biosensors. Regrettably, overall cancer mortality has hardly changed in thirty years. We are collaborating with the research group of Professor Greg Weiss to detect cancer much earlier, before metastasis occurs, in the hopes of impacting this problem. Together with the Weiss Group, we have been developing a new type of disposable biosensor that we hope will permit the detection of cancer markers in urine and blood. It can be disposable because the bioaffinity reagents and the transducer are both inexpensive. One outcome of the work so far is the development of an innovative bioaffinity medium, consisting of a conductive polymer and engineered virus particles, that can be electroplated in a single step, requiring a minute or two.
Project Leaders: Alana Ogata, Apurva Bhasin, Christine Liu.
© 2017, Reginald M. Penner