Today’s healthcare system is very reactive: only when a person feels ill does he go to the doctor. The doctor often then examines the patient, performs tests, and gives a diagnosis. Imagine a system, however, in which some of those tests would be unnecessary, because patients would have access to portable medical diagnostic devices for more timely, personalized healthcare.
Professor Zhenyu Li of the Department of Electrical and Computer Engineering is working with colleagues and students to develop technologies that will help make that scenario a reality. One of these technologies is a device called a “lab-on-a-chip” and is akin to a microelectronic computer chip. “We’re using nanotechnology to try to miniaturize conventional lab equipment,” says Li.
For time-sensitive diagnoses such as infectious diseases or heart attacks, such portable medical devices could change survival rates. For example, a person who is known to be at risk of having a heart attack could be given the lab-on-a-chip device, which he could use to test his blood for the presence of cardiac Troponin I, a highly specific biomarker whose concentration in blood shoots up dramatically when the heart muscle is damaged. If the biomarker is detected, he could seek treatment immediately, rather than having to send a blood sample to a lab and wait for results.
In spite of the pun, miniaturizing conventional lab equipment is no small task. Li explains, “With a computer chip, you are handling only electrical signals, but for medical diagnostics you have to handle biological samples, like blood or saliva, and you also need to add sensor components to the chip. It really requires a lot of expertise from different fields to make a complete system.”
For a lab-on-a-chip to be effective, the body fluid sample must be able to get close enough to the sensor, and this means that the electronics and sensing components must be integrated into the microfluidics device, the device that handles small volumes of body fluids. However, traditional microcomputer chips are made of a very rigid silicon substrate and require special packaging processes, which make integrating them with fluidics very difficult.
While other researchers are also working on lab-on-a-chip technologies, very few are trying to integrate all three components—microfluidics, optical sensors, and electronics—into a complete system in order to solve this problem. Working with Professors Mona Zaghloul and Can Korman, Li and his team recently found a way to do this by developing a technique that enables them to embed the microelectronics chip in the same microfluidics device. Their technique creates small channels in the substrate through which they introduce liquid metal in the same way they introduce fluid samples. The metal makes liquid-based electrical connections to the microelectronic chip, which enable the body fluid sample to get closer to the sensor. In addition, the device is very soft and can be made on a flexible surface that can be wrapped around a finger.
This is an accomplishment of which Li is justifiably proud. “I don’t think any other group has integrated the three thing—fluidics, optics, and electronics—all in one microsystem,” he claims. “This is a true breakthrough.”