Current research projects include:

• Hermit Crab Shell Selection: How do hermit crabs choose their shells? A team of undergraduate researchers are studying the relation between the surrounding flow condition and the type of shells selected by hermit crabs. They have found that shell selection in no-flow condition is generally based on the weight of the shell and the size of the shell opening. The shell selection at higher flow velocities is currently being studied; initial results indicate that the crabs will pick slightly heavier shells when surrounding flow velocity increases.
• Sea Lion Quiz Machine: A team of freshman engineers are constructing a device which is to be used to train Sea Lions at the New England Aquarium. The device was designed by Mechanical Engineering seniors as a part of their senior design project. The goal of the device is to aid in traning sea lions to answer yes/no questions, and to reward them with fish for each correct response.
• Butterfly Thermoregulation / Convection: Butterflies acquire the body heat needed for flight by basking in the sun. During basking, much of the heat is absorbed by the wings due to their large area. This heat is believed to travel to the body by convection. This project studies the effect of various wing position on the butterfly's body temperature by flow visualization and temperature measurements. The experiment uses a scaled model of a butterfly with heaters embedded in the wings to simulate basking. The model is submeged in a water-based solution, and flow around the heated wings is visualized by shadowgraph techniques.
• Butterfly Thermoregulation / Radiation: Butterfly wings are covered with small scales, which may consist of numerous thin films, causing thin-film interference. The amount heat absorbed by the wings during basking is affected by the altered absorptivity of the wings. The temperature distribution over the butterfly wing and body is examined while butterflies heat radiatively by a solar simulator lamp. Studying the way nature has optimized the butterfly thin film structures gives researchers insight into designing thin film structures for microschips so that they heat uniformly.

Research in the Spectral Research Laboratory include:

• Thin-film Structures of Butterfly Wing Scales: The complex microstructures of butterfly wing scales causes microscale optical effects such as thin-film interference, diffraction, and scattering. Thin-film interference is responsible for the bright iridescence seen in some tropical butterflies. Diffraction can be observed in other species, which exhibit different colors at different angles. These effects are studied using the Microscale Reflectance Spectrometer and are modeled numerically.
• Radiative Properties of Microelectronic Materials: Semiconductors and other materials used in microelectronics often undergo radiative heating processes. During these processes, controlling the temperature changes and uniformity of the wafer is critical in achieving manufacturing specifications. Being able to model and predict the temperature both temporally and spatially depend on the knowledge of the radiative properties (reflectivity, emissivity, and absorptivity) of the wafers in question. These properties, however, are often unknown due to semiconductors' complex properties, as well as the interaction between radiation and the small features on the wafers, such as thin films and patterns. In the laboratory, we study the effects of small patterns on the wafer's property by examining the microscale radiative effects on Si wafers. Furthermore, the changes in the properties at high temperature are studied using compact heaters.
• Microscale Rapid Prototyping: Microscale rapid prototyping is being developed to fabricate small 3-D structures by successive layering of thin polymer layers. The technique is similar to photolithographic fabrication method used in microelectronics industry. In this project, UV curing polymers are used for the fabrication of small structures, with possible applications ranging from microlens arrays to scaffolding for artificial tissues. This project began as part of the Summer 1999 Research Experience for Undergraduates program.

Summer 1999 High School Scholars Program

The High School Scholars Program is a four-week summer program sponsored by the Thermal Analysis of Materials Processing Laboratory. This program gives high school girls an opportunity for a hands on engineering experience, and allows a more thorough understanding of the field of engineering, and its applications. This unique experience allows participants to ask questions about the world around us and see obstacles that engineers face in the real world. Participants will be encouraged to use their creativity to solve practical problems, and use their imagination to question why things work the way they do.

During the Summer 1999 program, the high school girls worked on designing and building a museum exhibit on butterfly iridescence and thermoregulations. Visit their website for more information.

Student project homepages from Spring 1996:

• Visualization of Convective Flow Around Butterfly Wings
• Radiative Heat Transfer During Butterfly Basking
• Drag Force Measurements on Sea Anemones
• Cross-sectional Areas of Sea Anemones in Flow