Assistant Professor of Electrical Engineering Kaushik Sengupta and his team are developing a computer chip-based diagnostic system, which rests comfortably on a fingertip but contains hundreds of different sensors for simultaneous detection of disease-causing agents. The eventual goal is to use the chip in a handheld, portable diagnostic device that could be deployed in health clinics around the globe, especially in resource-limited settings.
The chip detects and measures the presence of DNA or proteins to help diagnose health conditions. Most existing methods for detecting these agents involve shining light on fluorescent labels attached to the DNA or protein and reading a resulting signal. However, in many types of tests, the signal is so weak that complex optical equipment is necessary to read the signal.
To perform this analysis using a simple handheld device, Sengupta is co-opting silicon chip technology similar to that found in personal computers and mobile phones. “This is a great technology for handheld medical diagnostic devices because it allows us integrate extremely complex systems in a single chip at very low cost. The vision is to unleash Moore’s law in diagnostics,” said Sengupta, referring to Intel co-founder Gordon Moore’s observation that processing power in computer chips has increased rapidly over the years.
The team starts with highly sensitive light-detecting components, or photodetectors, that are already ubiquitous in smartphone cameras, then adds new optical processor capabilities to the chip. The researchers found a way to re-wire the architecture of the chip so that in addition to carrying electrical information necessary for image processing, the chip also interacts with the incoming photons from the fluorescent light, and can block them out, allowing the signal that carries information about the test sample to be detected and processed.
This ability to integrate optical elements with electronics inside a single silicon chip is enabling the team to build detection systems for both genetic material and proteins. Millions of photodetectors can already be crammed into smartphone cameras and Sengupta plans to put hundreds or even thousands of such sensors on the new chip to create a platform capable of testing many agents at once. In addition to being cheap and robust, this “lab-on-a-chip” will be user-friendly. Sengupta and his colleagues envision that the chips will be used in a portable device similar to a smartphone that can use an app to analyze the fluorescence data and display diagnosis results in a clear, simple format.
To make the device truly portable, it will be necessary to develop a small and lightweight apparatus to isolate proteins and genetic material from blood or other fluids, and Sengupta and his collaborators are working on this challenge. “The entire end-to-end system may take another couple of years to reach, but we’ve demonstrated the feasibility of the approach,” said Sengupta, who collaborates with Professor of Chemistry Haw Yang. “Princeton provides the kind of environment that makes it easy to reach out to faculty members across the campus and to work on creative endeavors that cut across traditional disciplines.”
The initial work on the chip was supported by Project X, a fund established through a donation from G. Lynn Shostack S’69 for the support of exploratory research. The project involvesgraduate students Lingyu Hong in the Department of Electrical Engineering and Hao Li in the Department of Chemistry, Postdoctoral Research Associate Simon McManus and undergraduate Victor Ying. Lingyu and Hao were awarded a Qualcomm Innovation Fellowship for 2015-16 for this work.
-By Takim Williams