We report on a microfluidic platform for culture of whole organs or tissue slices with the capability of point access reagent delivery to probe the transport of signaling events. Whole mice retina were maintained for multiple days with negative pressure applied to tightly but gently bind the bottom of the retina to a thin poly-(dimethylsiloxane) membrane, through which twelve 100 μm diameter through-holes served as fluidic access points. Staining with toluidine blue, transport of locally applied cholera toxin beta, and transient response to lipopolysaccharide in the retina demonstrated the capability of the microfluidic platform. The point access fluidic delivery capability could enable new assays in the study of various kinds of excised tissues, including retina.

Graphene has attracted extensive attention in biological and biomedical fields due to its unique physical properties and excellent biocompatibility. We combine graphene field-effect transistors and scanning photocurrent microscopy with microfluidic platforms to investigate electrical signals in mouse retina. Remarkable photocurrent signals were detected from the graphene underneath optic nerve head (ONH) of the retina, where the electrical activity from this region can modulate the carrier concentration of the graphene and induce local potential gradients. These built-in electrical potential gradients can efficiently separate photo-excited electron-hole pairs, leading to strong photocurrent responses in the graphene underneath the ONH. We also show that no significant photocurrent signal was observed in the graphene underneath either dehydrated or fixed retinal tissues, verifying that the photocurrent responses generated in the graphene underneath the ONH were indeed induced by the electrical activity in living retina. This method not only provides a way to investigate electrical processes in living retinal tissues, but also offers opportunities to study many other cellular systems involving cell-cell interactions through electrical signaling.

with her Bachelors degree before moving on to Vanderbilt to finish her Doctoral degree. Upon completing her research at Vanderbilt, she joined the faculty at her alma mater where she has focused on thermal-fluids topics in teaching and humanitarian engineering applications in research.

At the Peugeot Center for Engineering Service in Developing Communities at Lipscomb University, seventeen years of experience have provided the foundation for a program that creates lasting impact. In comparison to other service learning or humanitarian engineering programs, the Peugeot Center is unique in that it achieves substantial impact on students, communities, and engineering professionals. This paper describes the model and mentoring employed by the Peugeot Center with supporting examples from a recent project. The case study describes a potable water system that was designed by a team of students, a professional engineer, and a partnering organization in Guatemala called ADICAY. Though the professional engineer and ADICAY supported the overall design work, the students supported the project by completing a site survey, designing the piping layout, and leading the onsite construction. Through mentoring from the professional engineer, the students developed skills in project management, teamwork, communication, and ethical decisionmaking. The professional engineer noted the opportunity to use their engineering skills to serve others as a primary reason for involvement. By partnering with ADICAY, the students learned about 2 2022: VOLUME 10 ISSUE 1 ADVANCES IN ENGINEERING EDUCATION The Peugeot Center Model and Mentoring Explored through a Case Study of the Design and Installation of a Potable Water Systemthe complex cultural, social, economic, and environmental impacts of their engineering work. The installed system provides potable water to 113 household taps in a rural Mayan community. A medical clinic held before and after the installation of the water system showed a reduction in water-borne illness diagnoses from 40% to 11%. Additionally, data from the clinic showed a lower rate of waterborne illness diagnoses in Setzimaaj (11%) compared to surrounding communities without potable water (33%). Overall, the success of the project is attributed to significant mentoring as well as the deep trust that was built in these partnerships. Lessons learned and best practices for employing a model similar to the Peugeot Center's are reflected throughout the paper.

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