Charles Stattelman is an apple farmer. He manages about 40 acres of apple trees on the shores of Big Stone Lake, near Ortonville, MN. One of the most important things for him and his trees, is the health of the soil. He must constantly monitor nitrogen and water levels, ensuring the soil is well-drained and up to USDA organic standards.

But what if there was a chip, a small sensor in the ground, that could monitor soil properties for you? A team of NDSU professors and the founders of local bio-composite developer, c2renew, are currently developing such a thing- a biodegradable soil sensor called the c2sensor.

The c2sensor prototype is a 2 by 2 cm chip, but it will soon be small and round, about the size of an acorn. The biodegradable soil sensor is attached with a passive radio-frequency identification (RFID) tag that re-charges the central processing unit (CPU), and can communicate real-time data on the soil, such as moisture, salinity, and chemical content.

A reading device attached to a tractor, a 4-wheeler, or potentially a UAV, is able to charge the CPU (so no batteries necessary), collect the data from the sensor, and store it in the cloud.

But the coolest part, said c2renew and c2sensor co-founder Corey Kratcha, is that the entire sensor is bio-degradable.

“You never have to go back and get it. It just bio-degrades,” Kratcha said. “You can go back and plant another set of sensors, and then they’ll bio-degrade.”

For Kratcha, who claims to have “scoured everything as far as competitive technology,” the fact that the sensor is biodegradable makes it stand out. Right now, he said, other sensors being designed are probe-like with a lithium battery, that must eventually be retrieved by the farmer.

The team is currently doing a full life cycle analysis on the c2sensor, but the estimated life is about 2 years, Kratcha said.

Biodegradable soil sensor created by a team of research superheroes

What began c2sensor was an epic collaboration of professors at NDSU, who wanted to combine their individual disciplines to create something new. I personally visualized this as sort of an Avengers like team, so feel free to do so as I describe each of their superpowers:

Chad Ulven, co-founder of c2renew and associate professor of Mechanical Engineering at NDSU, has studied bio-substrates for over 8 years. He’s the bio-composite master.

Justin Hoey and Rob Sailer, both Senior Research Engineers at NDSU’s Center for Nanoscale Science and Engineering, are experts in micro-cold spray research. They were able to develop a micro-cold spray that allows them to write circuitry at room temperature, rather than the standard high temperatures that would melt any sort of bio-based material. To create the c2sensor, they are able to write circuitry onto circuit boards made from a biodegradable thermoplastic, polyactide (PLA) flax.

Cherish Bauer-Reich and Nathan Schneck, also research engineers at NDSU’s Center for Nanoscale Science and Engineering, completed the team with an expertise in RFID and antennae research.

So what do you get when you combine experts in bio substrates, micro-cold spray, and radio frequency identification? The c2sensor.

“They all came together and brainstormed ideas. And ultimately the 100% bio-based sensor came out of that,” Kratcha said.

The greater value of the c2sensor

The technology was licensed in July 2014. But the c2sensor itself is still in development, Kratcha said. They will be doing trials of the biodegradable soil sensor this spring.

“There’s still a lot of development on the technology that needs to be done, but we’re going to be the ones to push as hard and as fast as we can to do it,” he said.



For Charlie the apple farmer, if the sensor is affordable it would “most certainly prove useful,” he said.

“Apple trees, especially when freshly planted, require frequent watering to produce the best yields,” he said. “Knowing precisely when and where to water would save a lot of time and money. A longer term chip might prove useful in determining where to plant new trees.”

And farming, Kratcha said, is only the beginning of where this technology could go.

“The nice thing about this is we can look at other markets that may have value for this,” he said. “How can a low-cost sensor be used in healthcare? How can a low-cost sensor be used in transportation?”

Learn more about the c2sensor, here.

Photos courtesy of Marisa Jackels and newswise.com.

