Biotoxicity

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.


Magnetic Fluids

In the magnetic fluids experiment, students will synthesize very small (~10 nm) iron oxide nanocrystals and examine the effects of "nano" on the magnetic properties that result. The nanocrystals are synthesized in solution using simple iron salts as precursors.  They are then homogeneously dispersed in water to form a colloidal solution or a ferrofluid.  This unique fluid has both the properties of a normal solution and the properties of a magnetic mineral (magnetite). That is, the magnetic fluid is a single phase solution that does not settle over time and it can easily flow or pore.  At the same time, the liquid is attracted to a magnet.  One interesting feature of a ferrofluid is that in the presence of a strong magnet, the fluid will form "spikes" that follow the field lines of a standard bar magnet.  The ferrofluid thus allows students to visualize the 3-dimenstional distribution of magnetic field lines in space around a bar magnet.


Nanowire pH Sensors

This workshop is based on the reversible chemistry of a conducting plastic (polyaniline or PANI).  When PANI is exposed to acid its conductivity increases; base reverses the effect.  Since the reaction with acid and base takes place mostly at the surface of the PANI, creating nanosized PANI fibers produces a system that shows large and rapid changes in conductivity in response to pH changes. These nanofibers/nanowires are employed in a hands-on activity where students design, engineer, and optimize gap electrodes in the construction of a pH sensor.  Vapors emitted from an acid (vinegar) or a base (a 0.1 M aqueous solution of NaOH) are reversibly detected by the sensors that students build.  Polyaniline nanofibers are a unique technological platform for device construction.  The chemistry of dispersions of nanofibers makes working with this polymer a fun and colorful experience.  Construction of sensors in this workshop is a multidisciplinary scientific task that leads to discussions of topics like organic semiconductors, nanotechnology, environmental engineering, and the chemistry of plastics that conduct electricity.




Photolithography

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.


Self Assembly

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.


Solar Cells

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.


Water Filtration

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.