Project Background: Human skin provides a two-way barrier that prevents potentially harmful chemicals or diseases from entering the body while slowing water as it exits the body. The outermost layer of skin, called the stratum corneum (SC), presents the dominant resistance to transport; the SC is composed of many corneocytes (dead cells) in a lipid bilayer continuum in a brick-and-mortar structure. In order to reach the bloodstream, any molecule on the surface of the skin must pass through the SC, so understanding transport in the SC is key to transdermal drug delivery design and setting dermal exposure limits to toxic chemicals.
- In Vivo Transepidermal Water Loss (TEWL) Experiments: To examine the effects of humidity and/or stretching on transport through skin, we conduct in vivo (human volunteer) studies. We have designed a stretching apparatus for constant strain uniaxial extension, and are currently refining an instrument that can carry out constant strain and constant stress extension and obtain important mechanical properties (see below); for studying effects of extension, we measure TEWL using the BioX AquaFlux before and after extension. For examining the effects of humidity on transport, participants place their arms in a humidity-controlled chamber and we measure TEWL across humidity levels.
- Mechanical Stretching Device Design, Building, and Control: We are refining the design of a device that can measure the mechanical properties of skin for test subjects or dermatology patients. The device uses a combination of linear actuators and load cells and interfaces with a data acquisition instrument to digitally process output voltage signals from the load cells. We hope to first validate the property measurement on subjects who do not have any disease affecting the mechanical properties of skin. We will then compare properties measured in a control (non-disease) group to those measured in a group of subjects who have a disease known to affect mechanical properties to determine if they show statistically significant differences.
- Finite Element Modeling: We are using the finite element modeling (FEM) program COMSOL to run simulations of transport across the skin as the lipid and corneocyte dimensions change with hydration or mechanical extension. To determine the extent of changes in SC dimensions with mechanical stretching, we are developing a mechanical model of the skin structure, including layers deeper than the SC.
1. A statement of your interest in research in general and in the project in particular. Please include:
- Why you are interested in this project,
- Which parts of the project most interest you,
- Information on your relevant background or desire to learn specified skills, and
- How many units you would be able to sign up for (typically between one and three) in Spring 2023 and Fall 2023 and briefly explain how adding these additional units per semester year would fit into your academic plan. Note that each unit requires three hours of research work per week plus meetings.
2. The names of two HMC professors (or outside research or internship advisors) who could provide references on your work style. Professors from project or lab classes might be especially good choices.
This highly interdisciplinary project covers many aspects of biomedical, chemical, mechanical, materials, and (some) electrical engineering as well as device design; it will give you experience with a wide range of experimental and/or modeling techniques, and has a rich body of work by previous students that you can build upon. Research students in the Lape Lab are able to sample multiple pieces of the project and focus on the 2-3 areas that interest them the most. Students on this team will have the chance to attend and present at the 2023 Gordon Conference on Barrier Function of Mammalian Skin. Additionally, you will work in a friendly and inclusive team environment and will be mentored by students currently on the team.