Wenzhuo Wu, PhD, Ravi and Eleanor Rising Star Assistant Professor in the school of industrial engineering at Purdue University, talks about a new heart monitor smaller and thinner than a postage stamp.
Let’s start by asking you if you could give us an overview of your latest project: the heart monitor?
Wu: For that project, we essentially use the PVA. It’s very common, probably one of the most widely used polymers in the biomedical field. People use it for all sorts of applications in biomedical treatment and people mostly use this for its biocompatibility and it does not take too much of its functionality. So, we kind of want to transform a very common effect which is called the triboelectric effect. It’s essentially a static discharge. You can imagine during the wintertime here in West Lafayette, it’s very dry. So, when you shake hands with some people else, you will feel shocked. That’s because you and the other person have a different surface work function, we call it, because you have different surface property, and it’s very dry, so you have a charge transfer. And that’s a very common universal effect. For example, lightning is also because of the friction between clouds. And we use that effect on a very small scale. We turn these PVA polymer devices into a stretchable device. And when we attach that device onto the skin, this small vibration on the skin induced by the pulse will be able to deform that PVA polymer because the polymer is very soft. So, it can be easily deformed. And when it deforms, there will be a contact and a separation, a very small gap will be induced between the PVA and the skin and that gap will actually generate a charge so we can harvest that electric charge and monitor their signals. Their electric signal, following closely to the pulse vibration. So, when you touch your finger on the skin, you can feel that, but you cannot see it because it’s a very small degree, but the device can pick it up very precisely. We can then monitor that signal generated by this device, induced by the vibration of the skin and we can now track and monitor the health status of the human because there are all sorts of library data you can refer to. So, you can check those three peaks monitored from this human being and you can calculate the distance between those peaks, the relative peak intensity of those three peaks. Then you can generate a bunch of rich data to let the doctor tell you whether these people are healthy or whether you have some potential problems with your heart.
So once the monitor is on the skin … if I correctly understand there’s a computer interface and everyone can look at the data? Can you explain that to me again?
Wu: So, essentially what you are looking at here, are a bunch of different small pieces here. You can see this a small piece of device. This is made of PVA and it is very soft. You can see that it can also be stretched. The way we attach this device is it mounts to the skin. We will also attach electrodes. So, the electrode will now be connected to a computer for data acquisition. And then we have the software on the computer, so you can read the data in real-time. So that’s the older version which is a wired version. Right now, we’re also developing the wireless version. So, imagine that you can attach this to your wrist or your body. Then there is a small chip attached to this one which can collect the data and extend it to your cell phone. So now, not only you but also maybe your primary doctors can also monitor, can get alerts if there’s anything wrong with you or if there are any other alerts sending out from the device.
So that almost looks like a tiny piece of Scotch tape. Could you describe it?
Wu: So this looks like a small piece of Scotch tape like you said. We can easily attach it onto any part of the body because the material itself is very soft, it’s also very thin. Just like the tissue from your top skin, it’s very soft so you can see that it cannot support its own weight. It will collapse because it’s that soft. And because it’s soft, we can easily attach it onto the skin just like a Scotch tape without using additional tape.
So it just sticks— it has an adhesive property?
Wu: Yes, for a certain period time, of course not indefinitely, but for a certain period time. And the PVA is also biocompatible and biodegradable so we can engineer the property of this fume to make it self-degrading over time. So, imagine that when you are attaching this to your skin, one day it will dissolve when you take a shower, and the second day, you can attach a new one.
What are the real-world benefits of having something like this available to patients?
Wu: So right now, the devices for the hospitals and doctors for cardiovascular monitoring are very bulky, and also, there are a bunch of wires, so you need to attach those wires onto the body and many of those devices are very expensive. Of course, now we have these wearable devices, like a smartwatch or FitBit. Those devices can also help you monitor, but those devices require power, so you have a battery. For our device, it actually generates electricity from your pulse motion. So, the pulse vibration would deform this device and it generates power. So essentially, we envision that we can significantly reduce the power consumption for the device, and you don’t need a battery here to your body.
Wow. So how far along in development are you, Dr. Wu? When could you potentially see this finishing?
Wu: Oh, that’s a very good question! So I guess that’s why we are working very closely with the Purdue Research Foundation. We have already filed a series of patents, disclosures for this one and related technologies. So right now, I should say it’s still in the early stage, but I’m considering starting up my own company with the help of PRF and also Purdue Foundry to commercialize these technologies. And, at the same time, we are also very interested in seeking resources and help from any other external parties who are interested.
So did I hear you correctly? You’ve already filed for a patent?
Wu: For this one and the related, yes, already filed patent disclosures, for two of them.
So, in terms of the timeframe, it’s hard to tell because it’s dependent upon development, funding, etc.?
Wu: Yes, but I think of this paper as a project itself, I think a good demonstration of a proof-of-concept. Right now, in my lab, I just walked out and my students and my people are working very hard. So we are now working on the TIL technology run at this level-3-type of work, so that’s a little bit more advanced, still a full-concept demonstration, but it’s more advanced in terms of the system integration, like the one I just mentioned, how we integrate the wireless component to the device to make this system entirely wireless or tethered instead of a wired connection.
Well, that was my next question there. Is there a watch or a device that someone would wear that would pick up the signal?
Wu: That’s a very good one. So, actually, we can attach this to a watch. And as long as there are electrodes that can be connected to the watch, which can be easily done, then the watch itself can be used as the data acquisition and transmission portal to sending out the data to the cellphone or to your computer instead of cramming a whole system onto this device. So, this can be used as an add-on component to your watch.
You had mentioned that it can be worn anywhere, but I know we keep pointing to the wrist. Is it, ideally, best suited for the pulse that’s at the wrist?
Wu: When diagnosing a patient, the first thing they will do is to put their fingers, three fingers, onto the pulse, and to measure. So, the more I’m looking at my device, the more I’m starting to think, probably, those experienced doctors, they’re actually using their fingers to do very complex mathematic computation in their mind without even knowing it. And they analyze the data because the principle is the same: they use their fingers to feel the vibration, we use the device to measure precisely the vibration and we analyze the data. So, I would say that the wrist is a very good position because it’s very easily accessible. In other places like the chest, there might be privacy issues. But the other part that could be potentially important is the neck. So there are a lot of the blood vessels here so you can measure, you can feel the pulses and use the device to measure it. So, I think the neck and the wrist would be the most ideal.
So regarding the static electricity charge, can you feel it? Are there any little shockwaves that you feel in between?
Wu: No, because you will have the shielding device. You will have, essentially a shield, on the device. Just like you’re wearing a watch, there are probably over millions of electric components in your watch, but you won’t feel any electric leakage. If that happens, we are in huge problem. But nowadays, in system integration and packaging, they are doing a great job.
Interview conducted by Ivanhoe Broadcast News.
END OF INTERVIEW
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