Colloidal silver is an antifungal agent used in bandages. Unlike silver ion solutions, colloidal silver is toxic to microbes, without harming humans The Biotoxicity Experiment tests the ability of colloidal silver to inhibit the rate of yeast cellular respiration (carbon dioxide production), as compared to other silver containing compounds. This experiment highlights the fundamental concepts of respiration, data quantification, and the use of nanotechnology for real world applications.
In this experiment students use light to transfer a pattern onto a surface, ultimately resulting in a network of very small metal wires on a plastic board. The pattern is transferred by placing a mask with the wire design on a plastic board. The board is coated with a copper film that is covered with a light-reactive polymer. The polymer is exposed to UV light through the mask to make a pattern in the polymer. The metal under the exposed polymer is then chemically etched, leaving only small wires on the surface of the board in a pattern determined by the mask. Students can then measure resistance as a function of wire length and wire diameter to explore both the positive and negative resistive aspects of making thing small, but close together. This top-down approach to nanotechnology is commonly used in manufacturing circuit boards for computers and other electronics and students will learn the very simple chemistry and physics at the core of photolithography.
In the self assembly experiment, students learn how foam "atoms" can spontaneously form order structures. To mimic the effects of thermal energy, the atoms float in a pool of water; shaking the pool is equivalent to raising the temperature. The atoms all contain magnetic elements that can be used to create attractive or repulsive interactions between atoms. Contrary to our intuition, students find that attractive interactions between molecules do not result in order structures, but rather in agglomeration and formation of complex clusters. By contrast, repulsive interactions create highly periodic arrays. The interaction energy between "atoms" can be thought of as an enthalpy that can be used to tune array structures. This type of self assembly is at the root of both atomic and supermolecular structures. It enable to complexity of biological systems and is one of the key methods for creating arrays with nanometer scale periodicity.
A comprehensive study on solar cell, from device fabrication to performance characterization, will be presented. Several concepts such as the importance of solar energy to the environment, the effect of nano-science on solar cell performance, and the similarities behind the concepts of photosynthesis and solar cell will be discussed.
Super Hydrophobic Surfaces
The superhydrophobic surfaces experiment blends elements from chemistry, biology, and physics to vividly demonstrate how the incorporation of nanoscale texture at a material’s surface can lead to dramatic changes in certain physical properties such as wettability. Nanoscientists often find inspiration in nature. In this experiment, students will assemble silver nanoparticle films onto copper surfaces using an electroless galvanic deposition technique. After treating the nanoparticle films with a hydrophobic, “Teflon-like” coating, these surfaces are able to repel water in a manner that resembles the surfaces of lotus leaves or the feet of water strider insects. The interaction of these nanotextured interfaces with water is said to be within the superhydrophobic regime, where the contact area between water droplets and a surface is minimized until the droplets become nearly spherical and literally roll or skip off the surface. Students will learn basic concepts in surface chemistry and discuss emerging industrial applications for materials with these unique characteristics.
In this experiment activated carbon is used to filter various color dyes from water. The interplay between the role of the size of the carbon particle size as well as the size of the dye molecule is explored.
Portable electronic devices like cell phones and laptops exist because of energy storage in the form of batteries, capacitors, and supercapacitors. In vehicles, electric engines have much higher energy efficiencies than combustion engines, and they are enabled by energy storage devices. In addition, energy storage is necessary for some renewable energy sources, such as solar and wind, which are inherently intermittent in nature. Much research is being done with nanosized materials to make energy storage devices cheaper, last longer, and charge faster. In this experiment, students will be making and using supercapacitors. Supercapacitors are energy storage devices that utilize the high surface area of nanostructured carbon to store charge. This type of charge storage is called non-faradaic because no redox reactions take place: charge is stored through the formation of an electric double layer between the nanostructured carbon and the electrolyte.