College of Engineering News • Iowa State University

A Fitbit for Plants

Image of corn connected to electronic sensors at Iowa State's Plant Sciences Institute.
Liang Dong, professor of Electrical and Computer Engineering at Iowa State
Liang Dong, professor of Electrical and Computer Engineering at Iowa State

We all wear or know someone who wears a fitness tracker, or an activity monitor. But what sort of impact could be made on food security if we had a tracker for our plants’ health?

In this episode of Factor Analysis, we speak with electrical engineering expert Liang Dong, a professor in the Department of Electrical and Computer Engineering at Iowa State University.

Dr. Dong is in the process of developing a Fitbit-like device for crops like corn with the potential to lower the amount of money farmers put toward water — resulting in economical farming methods and cheaper foods on grocery store shelves.

Announcer: Welcome to Factor Analysis, an in-depth conversation of engineering knowledge from the classroom to the field, and topical issues surrounding work and life from an engineer’s viewpoint.

Sarah Hays: I’m Sarah Hays, and I’ll be your host for this episode of Factor Analysis.

Water is a resource we use every day — to shower, wash dishes, or have a drink. But it comes at a cost. Water can quickly become a very costly resource, especially for farmers. Growing acres and acres of crops, water is used by the ton — a necessity that doesn’t come cheap. And when spending so much money on water, the price of fresh produce on grocery store shelves rises exponentially.

Dr. Liang Dong, a professor in the Department of Electrical and Computer Engineering at Iowa State University, is working with Iowa State and the University of Nebraska-Lincoln to develop a device with the potential to lower the investment farmers put toward watering their crops — resulting in economical, more affordable farming methods, and lower prices at the grocery store checkout.

Known as the “Plant Fitbit,” this device is ultimately a sensor that is worn on the stalk of a plant. Similar to an activity monitor worn by humans, the sensor measures internal sensations of the plant, specifically the ability of a plant to uptake water. By monitoring how fast different plant varieties absorb and transport water in different environments … and explaining the differences in drought tolerance … plant scientists could select and breed specially designed plants that require less water to grow.

Using heat, the device will be able to measure the flow rate of the water being transported through the plant.

Liang Dong: “We will use a thermal method to measure the water movement within the plant. Imagine you have a wearable patch. That patch is going to be attached to the plant body. Then, we have multiple smaller heaters attached to the patch. As the water moves from low to high, the water will take away heat.”

Sarah Hays: So by measuring the temperature change of the sensor attached to the plant body, you can get information regarding the flow rate of the plant. But how do scientists retrieve the information from within the sensor?

Liang Dong: “So, the information from the device is transmitted from the device to the cloud — through wireless technology. And then, we will put multiple sensors across the field, to collect the information about water transport from soil to the plant at different locations of the crop field, so that you can get a map of water states not only in the soil, but also in the plant.”

Sarah Hays: Here in the Midwest, we all know the weather can reach extremes, and is very unpredictable. Dr. Dong says the device takes these factors into consideration, and is designed to weather the elements.

Liang Dong: “Weatherproof is very necessary for devices being outside. One of the undergraduates in the research laboratory is working on a weatherproof coating for the device, so that device can be used even on a rainy day. The design of the sensor will lead it to long term measurement. Our idea is that when you see plants about knee-high, you put a device on the plant and keep the device there. We want to capture all the information from the beginning of the plant to harvesting. The technology that we are using for this type of device is a wearable electronics technology, quite similar to the wearable electronics technology for a human being, so we are accommodating some things for the plant. For plants, you see it becomes bigger and bigger, so we have to create some innovations in the device design so this plant fitbit is flexible.”

Sarah Hays: This plant sensor seems very technologically advanced and durable, a bracelet for crops to wear, very similar to the fitbit or other wearable activity tracker many humans use in their daily life. But for us, these devices aren’t really cheap or always affordable. How affordable will this plant device be for scientists or farmers to use?

Liang Dong: “The Plant Fitbit itself is a conceptual innovation. Now, we are doing some technological innovation, trying to gain both high performance and low cost — we have to take care of both parts. Eventually, each sensor may cost just less than a dollar, which is very affordable. So far in the laboratory, the cost is much more than the targeted cost that we are aiming for, but we have figured out where we can improve so that eventually we can be at the goal of having the device in people’s hands at less than a dollar each. We use something called microelectronic mechanical systems, or MEMS technology. That is the method for making a semiconductor chip for computers. In order to use that technology for the plant fitbit, we have to do some modifications so that we can use the conventional methods for non-conventional devices. If that happens, then the cost of the device will be lowered.”

Sarah Hays: This definitely sounds like an energy- saving way to reduce water usage in farming. So after this device allows scientists to selectively breed plants for the best water uptake performance, crops will need less and less water over time. How does this practice shape the agricultural landscape for countries with a very dry climate? Or developing countries where water is often scarce?

Liang Dong: “For developing countries, definitely this device will be very useful. In africa, for example, the environment is very dry, so how can you grow crops or plants there in a dry environment? Using the sensor, you can get information about the water uptake of the plant. So scientists use that information to develop plants that are very good in Africa.”

Sarah Hays: So, this device could essentially lower cost at nearly every link in the food chain. I asked Dr. Dong how universal the device is to get a grasp on how wide-reaching the impact could potentially be.

Liang Dong: “Our first species is corn, and we have been working with plant scientists here. Outside of Iowa State, like at the University of Nebraska-Lincoln, they are also testing those devices on corn, and we are also looking at whether or not this type of device could be used for other high-value crops.”

Sarah Hays: We know in Iowa, there’s plenty of corn. But what makes Iowa State such a good fit for this project?

Liang Dong: “This is a project that needs expertise in both engineering and agriculture. We have various strong expertise in engineering, and we have very strong expertise in agriculture, of course, Iowa State. Here, in Iowa, we are more interested in fertilizer, nitrogen use, but I have a collaborator in Nebraska where they are more interested in water. So this project, basically, is a collaborative project with the University of Nebraska- Lincoln and we are going to test our devices mainly over there in the department of agriculture. So far, we have designed the sensors, and the students are building the devices in the laboratory. We are testing some parts of the devices, and we expect that sometime in the summer we will have a prototype, and we plan on getting it to the hands of our plant scientists for them to test in the greenhouse before we move them to the field.”

Sarah Hays: So once the prototype is complete and the device is commercialized, who exactly is the end user of this plant fit-bit device? Is it a farmer, or a plant scientist, or a gardener at home?

Liang Dong: “Our initial users will be plant scientists, because they want to select and breed good plants. And then, I think breeding companies will be interested in that, because they are interested in selecting and breeding at a larger scale. And then, I would say the farmers, when the cost goes down, will be interested in that.”

Sarah Hays: When it all comes down to it, what we really want to know is how this will affect the general public … the economy. How will this device change our daily lives?

Liang Dong: “The goal of this device is to get information about water transport, especially the water moving speed inside the plant. Imagine when it rains, only in the morning, before the sun comes out, can the plant uptake water before the land becomes dry? The plant can uptake water efficiently, so that when there is only a tiny amount of water in the soil, the plant can absorb — uptake — to the maximum extent. With this information, plant scientists will be able to select and breed, specially design the plants that require less water to grow and are able to uptake water when there is only limited water in the soil. That will help farmers manage to grow crops in the face of variable weather and with lower rainfall. Farmers will be able to lower the amount of money that they put to the water, therefore lowering the cost of the grocery store food you see on the shelves.”

Sarah Hays: And the cost of food is something that would potentially benefit everyone’s bottom line.

And that’s the bottom line from Dr. Liang Dong and this episode of Factor Analysis. I’m Sarah Hays, thanks for listening, and don’t forget to hit subscribe wherever YOU listen to podcasts.

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