Ask a Caltech Expert: Chiara Daraio on Wearable Devices To Track COVID-19

Daraio is the G. Bradford Jones Professor of Mechanical Engineering and Applied Physics. Her work is focused on developing new materials with advanced mechanical and sensing properties for application in robotics, medical devices, and vibration absorption. She developed new materials and methods for acoustic imaging and thermal sensing in medicine and health monitoring.

In a February 2021 webinar, Daraio talks with Caltech content and media strategist Robert Perkins about how her work contributes to new wearable medical devices.

The questions and answers below have been edited for clarity and length.

Can you tell us a little bit about your project? What have you been building and why?

In the last five years or so, we became very interested in exploring the use of new materials for wearable devices—in particular, devices to track different medical markers and to monitor diseases, like diabetes, from the comfort of a patient's own home. In this context, we've been working on developing polymeric materials that have record-breaking temperature sensitivity. We know that temperature is a recognized marker for several medical conditions. That includes viral infections, like COVID-19, but also wound healing, sleep disorders, fertility, and so on. The polymers we created mimic biological polymers found in natural systems and are incorporated in devices that can accurately measure the body core temperature from the skin of a user.

How does that work?

The polymers we created have a structure that responds to changes in temperature by changing conductivity. In the polymer, this has to do with changes in ionic conductivity, which can be read as changes in electrical current when the polymer is incorporated in a wearable device. The structure of our synthetic polymers is based on molecules that are crosslinked by metal ions bridges. When temperature increases, the metal ions increase their conduction. In a simplified sense, you could imagine the polymer's chains as the zipper of a jacket: as the temperature increases, the molecules "unzip", freeing the ions to conduct more easily.

Why do we want to measure core body temperature? What does that tell us?

Core body temperature is the temperature of the internal organs of our body. The human body maintains its core body temperature within a very narrow range of temperatures. And this is different from the temperature that you may measure on your skin. Everybody has cold hands and the skin temperature fluctuates a lot more depending on the external environment, whether you're outside on a hot or a cold day. However, the organ's temperature, or the core body temperature, is a marker for infections and a marker for many stressors in the body. So, being able to read accurately core body temperature can inform many medical decisions that can be related to viral infections, like in the case of COVID-19, but also to many other conditions that can be chronic in patients.

This device is also paired with an algorithm, correct? Can you tell us a little bit about that?

In the simplest scenario, we had envisioned developing a personal health care management app that would record temperature and combine it with other health information provided by the patient or a health care provider. One area of emphasis we've been initially interested in is wound monitoring for diabetic patients or patients confined to wheelchairs. Temperature is a clear indicator of inflammation in the wound, and such an app would be useful to remind users to move or care for the wound appropriately.

COVID-19 was the trigger for us thinking about how to pair these devices with smarter algorithms that would not only read the temperature but do something more with that information. This became a separate research project, inspired by the stay-at-home orders that have turned our own everyday lives upside down. Together with collaborators at Caltech, UCLA, Columbia University and MIT, we imagined creating an app that tracks location data but also tracks COVID test results along with self-reported symptoms or temperature-sensor readings from our own devices and others'. We developed an algorithm that learns from all the different data and calculates the personalized risk of COVID-19 exposure for each user.

Think of it a bit like weather forecasting: There is an app that communicates to each individual user the likelihood of rain, and users make an educated decision on whether or not to leave the house with an umbrella. Such information in the context of COVID-19 would enable users to make independent decisions about their individual degree of social distancing. For example, the app could tell you: "Hey, there's a high risk at Caltech, so don't go to Caltech today or don't go shopping today."

You've outlined a lot of the benefits we could reap from wearable medical devices, but what about the privacy concerns from sharing all that information?

Every time we share information online, privacy is and should be an important consideration. However, there are mechanisms already in place to anonymize tracking location data and medical data. You can think about what already exists in the many health data apps and devices that we all use. That information is stored on the phone or in the cloud in a secure and safe manner. We think it is possible to incorporate the standard state-of-the-art approaches for safe data handling in the algorithms we are envisioning and developing.

Here are some of the other questions addressed in the video linked above:

• What else can be done using these sensing materials?
• How long will it be until this wearable sensing technology is available on the market?
• Will people still use this technology once the pandemic is over? For what purpose?
• What might personalized medicine look like in the future?

Learn more about viruses on the Caltech Science Exchange:

• How Do Viruses Spread?
• How Does Disease Modeling Work?