Little sensors solving big problems

Biomarkers are measurable substances inside our bodies that give scientists and medical professionals a hint that we might have a certain disease, like cancer or Alzheimer’s, or have been exposed to a toxic chemical. Biomarkers are typically measured in blood samples or biopsies, which can range from a minimally invasive sample taken from the skin or a more invasive sample from within the body. Dr. Judith Su, the director of the University of Arizona’s Little Sensor Lab, is looking to change the way we detect biomarkers with her tiny, non-invasive optical sensors. Dr. Su is an assistant professor of optical sciences and biomedical engineering, assistant research scientist in chemistry and biochemistry, and BIO5 member. 

Talk to us about your diverse path into sensors – how much of that was planned versus organic, and at what point did you realize you’d be starting a lab to develop small sensors to solve big problems?

In the beginning, I chose mechanical engineering because my dad was a mechanical engineering professor, so that was what I had exposure to as a child. I also really appreciate what engineers do for society, so that was a natural step for me. 

When I was studying mechanical engineering, a lot of the interesting applications that people were doing were more biology-related, where people really wanted to obtain a molecular level understanding of things. That part – the biological direction – organically developed for me. 

In terms of starting my lab, that was something I’ve always wanted to do - the academic path always appealed to me. Some people know what they want to do, and I was one of those one of those people, so starting a lab was an easy decision to make.

Let’s talk a little bit about sensors. Describe how you view sensors – what has been typical in the past in terms of biomedical application, and how do you make your sensors unique?

I view sensors as a way that you can interact with your environment. The most common sensors people might think of are pregnancy tests or glucose sensors for diabetes, and now with the pandemic, people are very familiar with COVID tests and blood oxygen sensors. Those are probably the most well-known and the most commercially successful sensors. 

The impact we were hoping to have with our sensors is on medical diagnostics and environmental monitoring. We look at biomarkers for diseases like cancer or Alzheimer's, and we're also really interested in environmental monitoring applications like air pollution or looking for toxic industrial chemicals.

I think people can see, from incidences like Flint where there's contaminated drinking water, how important it is to be able to get information about your environment because it really affects your health.

You’re the director of the Little Sensor Lab, so can you also describe how small they are?

Our sensors are about 100 microns in diameter, so that's about the width of a human hair. They’re really small, but we’re hoping to use them to have big impact on society.

What are the steps you go through to keep moving the needle forward on smaller, less invasive, faster sensors?

First, I try to keep myself abreast of the current state of the art: what are the current technologies, and how do we compare.

In terms of how we make things smaller and faster, we do like, for example, a lot of computational modeling so we can really optimize our system. There, I think we really try to be guided by theory and simulation.

What's also great about it is so since we rely on a like a lot of other technologies like electronics, these fields are also rapidly developing, so, for example, when people make smaller batteries, these are always things that we can take advantage of.

We try to stay really on top the latest advances and try to follow a bunch of different fields to see what we can use.

Do you find yourself collaborating often, and if so, how does that help you in your research?

Collaboration is very key - we've benefited a lot from collaborations. When we have great collaborators, we can go a lot further in terms of the impact that we can make.

One great collaboration we have is with the larger group at Caltech. They are a computational chemistry group, and we have this exciting project with them on screening drugs for COVID-19. Their expertise is computational chemistry, so they can do virtual screening of thousands of drug compounds. That's not our expertise, but then we can combine that with our sensor expertise and use that to do drug discovery. We're also working with them to look for non-addictive opioid alternatives, so that's an example of where that's a field we really wouldn't have been able to do this without them, and our experimental validation is helpful to them as well.

We also collaborate with other groups on discovering new types of biomarkers for Lyme disease or ovarian cancer. Those are examples where we work with groups that are discovering new biomarkers, and we're working at detecting those biomarkers at the earliest possible stages, hopefully before physical presentation of symptoms. Early detection leads to better survival outcomes, so that's what we're really trying to do here.

We also collaborate with other chemistry groups and making our sensor as selected as possible - we have very sensitive sensors, but we don't want it always giving us a signal when we're looking at things that we don't want it to detect

Can you talk to us about one of your technical processes called FLOWER?

Our sensing system is called FLOWER, which stands for frequency locked optical whispering evanescent resonator. 

Our sensing element is this little glass donut that's called a migratory optical resonator that’s about 100 microns in diameter. FLOWER is the combination of that with electronics and other ways to improve our signal to noise ratio.

The light is essentially trapped within these little glass donuts, much like how light travels through optical fiber that’s bent back on itself, so it constantly goes around and around. That's what gives us our high sensitivity - the light is continuously interacting with things that are bound to the surface of the sensor, and so every time it does that, it gives us a signal we can read out. 

We’re hoping to apply to like lots of different things, like detecting COVID, water quality monitoring, environmental monitoring of air pollution monitoring…all sorts of things.

That's the great thing about working in a collaborative environment - sometimes people will contact us when they hear about our technology and will bring to us applications that we've never even thought of. I really enjoy that collaborative part. 

I know you find it very fulfilling to be a mentor and help others on that path. For someone who is watching or listening that might be interested in a career like yours, what are some skills they should start refining? What are your tips and things you've learned along that path in the early stage?

I think it's important to be persistent and to be very honest about the work you do.

Sometimes there's a result that people like to see, but the more important thing is for it to be the true result. Sometimes people can lose sight of that, but eventually what's going to stand the test of time is what's real. It's important when you do your experiments, you try to be as faithful as possible to what you think is really, really going on and not try to see something just because you want it to be a big discovery. 

I think it’s also important to recognize that setbacks are normal. If it was something that was easy to do, then people would just do it. If something doesn't work how you expected, that's often where big discoveries are made. It’s about not taking for granted that things are going to work out quickly or you know work out the first time and persisting and not getting discouraged. It’s important to be thinking of ways around the problem or new solutions to the problem and having confidence that things will work out in the long run.

You have a baby girl, and you’re expecting a baby boy this spring. We’re about to celebrate the International Day of Women and Girls in Science on February 11, and a lot of people think women can’t both have a family and be great at science. Can you speak to that? How do you debunk that myth?

I always knew I wanted to be like a mom.

I don't think you people can truly understand how much work is involved in being a parent until you have children, so the advice I would give to people is to make sure you choose a supportive partner. It would be something that's really difficult to do by yourself, so I think that's something you can make a really conscious, intelligent decision about. Know that they’re going to be there for you to help out. 

Also know to ask for help - parenting is 24/7, and if you want a job, too, you're going to need childcare support.

You received a $1.8M grant in 2020, so can you tell us a little bit about the work you’ve been doing with that grant?

That is a fantastic grant by the National Institutes of Health called an R35, called MIRA (Maximizing Investigators' Research Award), that funds the body of work in the investigator’s lab, which offers a lot of flexibility. We’re using it to fund all our biomedical sensing work, including our work in Alzheimer’s and cancer, and our next generation sensing platform.

We like to think of our scientists as superheroes, so if you were a superhero, what would your superpower be?

If I could have any superpower, it would probably be the ability to prevent death and save your loved ones.

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