Abstract
While my technical project of microfluidic impedance cytometry and STS project on photolithography operate within different subfields of electrical engineering, they are connected by two common challenges. The first is engineering is not an individual effort, and designs must align with the systems in which they operate to be successful. In completing my capstone project, I have had to design hardware that sits squarely between the digital world and a microfluidic sensor. In a similar light, ASML sits between the semiconductor industry and the tools that make production possible. Secondly, both projects encompass fabrication. In my own PCB design process, fabrication constraints, turnaround times, and manufacturer capabilities directly shaped what was possible. In my time working with the Biophysical Microsystems Group at UVA I was able to learn more about the photolithography process as their microfluidic chips are produced in house. Translating something from idea to design, and from design to production are steps that get more exponentially complex as devices continue to shrink. Technically sound designs are meaningless if they cannot be economically produced.
My technical project of on-chip impedance cytometry utilizes a high-throughput microfluidic technique that characterizes individual cells by measuring the changes in electrical impedance as they pass through a controlled electric field. Current techniques for measuring impedance are costly, bulky, and have high latency. This project aims to fill an existing gap in current cytometry technologies. Currently, on-chip fluorescent microscopy and off-chip optical flow cytometry are the primary tools for cell analysis. On-chip fluorescent microscopy is limited by its reliance on markers that can alter results, damage cells and can’t be used across all cells. Off-chip optical flow cytometry has its own limitations: a laser that often damages cells and a highly manual process that requires skilled professionals in a lab. Despite the limitations of current methods, they are still valuable tools. However, there is a gap to fill. Our project is a lightweight, high speed impedance analyzer that will generate electrical signals, process impedance sensor data, and trigger a sorting mechanism with a delay of less than 20 ms. Our design will incorporate a signal generation module, lock-in amplifier, analog-to-digital (ADC) and digital-to-analog (DAC) converters, and a system-on-a-chip (SoC) implemented on a printed circuit board (PCB) to quickly measure impedance signals.
During my STS research I discovered that despite the omnipresence of the products produced with photolithography, it remains largely invisible to the general population. I examined the rise of ASML to the top of photolithography to understand how technological development is actually shaped. Early on, ASML was responding directly to industry demands, competing with Canon and Nikon by solving immediate manufacturing problems. As the technology matured, development stopped being about any one firm’s strategy and came down to what the broader network could support, which is clear in the failure of 157nm lithography. Being technically ahead did not matter if the rest of the system could not follow. ASML’s advantage came from building strong relationships with suppliers and listening to customers, allowing it to move with these constraints instead of trying to force a directive. By the time EUV emerged, ASML had positioned itself at the center of the network and was defining the trajectory of the industry. This shows technological success depends on alignment with the system, not isolated technological advancements.
Considering my projects together highlights how engineering decisions are shaped by more than technical requirements. Actor-network theory shows how outcomes emerge from interactions among firms, materials, and constraints, while my PCB design required similar attention to manufacturing limits, component availability, and system reliability. In both cases, ignoring these factors would lead to abject failure, regardless of technical quality. This reinforces ethical engineering is not only about intent, but about understanding how designs function within larger systems. Designing a medical device without considering manufacturing tolerances or failure modes injects real risk, just as developing lithography technology without collaborating with the broader network led to failure for ASML’s competitors. STS perspectives support responsible engineering by allowing designers to account for the full system in which their work operates. In both cases, constraints are not obstacles to overcome but defining features of the design process.
I would like to thank Dr. Nathan Swami and the Biophysical Microsystems Group at UVA for their guidance and support, which helped shape both my technical design and my understanding of fabrication processes. I would also like to thank Dr. Keith Williams for his guidance throughout my time at UVA and for helping secure the additional funding that made this project possible.
