Gizmorama - September 6, 2017

Good Morning,

Hey, farmers! Wouldn't you like to know if your crops are a bit parched? Penn State University has a new sensor for you!

Learn about this and more interesting stories from the scientific community in today's issue.

Until Next Time,
Erin

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*-- Electric leaf sensors let farmers know when their crops are thirsty --*
New leaf sensors could help farmers keep their crops hydrated without wasting water.

In a new proof-of-concept study, researchers at Penn State University detailed the abilities of their plant-based sensors, which can measure a leaf's thickness and electrical capacitance, revealing whether it is parched or hydrated.

Researchers tested the sensor on tomato plants growing in a controlled environment. They used a soil-moisture sensor to monitor the saturation of the peat potting mixture. As the well-watered peat mixture was allowed to dry out, the researchers observed the changing readings from the leaf sensor.

By measuring the impact of a decreasing water supply on a leaf's thickness and electrical capacitance, researchers were able to develop an algorithm to predict when plants are getting thirsty.

"Leaf thickness is like a balloon -- it swells by hydration and shrinks by water stress, or dehydration," researcher Amin Afzal, a doctoral degree candidate in plant science at Penn State, said in a news release. "The mechanism behind the relationship between leaf electrical capacitance and water status is complex."

"Simply put, the leaf electrical capacitance changes in response to variation in plant water status and ambient light," Afzal said. "So, the analysis of leaf thickness and capacitance variations indicate plant water status -- well-watered versus stressed."

Afzal -- who described the sensor in a paper published this week in the journal Transactions of the ASABE -- believes his sensor could deliver information about a plant's water status to an irrigation system.

A central computer with smart learning software could used the information to decide when and where to deploy water resources, he said. Eventually, all of the information could be delivered wirelessly and sensors could be powered by solar cells.

"I believe these sensors could improve water-use efficiency considerably," said Sjoerd Duiker, an associate professor of soil management at Penn State. "Water scarcity is already a huge geopolitical issue, with agriculture responsible for about 70 percent of world freshwater use. Improvements in water use efficiency will be essential."



*-- New nano-sized device can lift 165 times its weight --*
Researchers at Rutgers University have developed a tiny machine with superhuman strength. The device can lift 165 times its own weight.

The miniature machine weighs just 1.6 milligrams, but can lift 265 milligrams several hundred times in a row. It's power is derived from the loading and unloading of ions between super thin sheets of molybdenum disulfide.

By converting chemical energy into mechanical energy, the device replicates the actuator power of a muscle.

"We found that by applying a small amount of voltage, the device can lift something that's far heavier than itself," Manish Chhowalla, a professor of material science and engineering at Rutgers, said in a news release. "This is an important finding in the field of electrochemical actuators. The simple restacking of atomically thin sheets of metallic MoS2 leads to actuators that can withstand stresses and strains comparable to or greater than other actuator materials."

The small but powerful actuator could be incorporated into a wide variety of electromechanical technologies, from robots to airplane wings.

Molybdenum disulfide, or MoS2, is an inorganic crystalline mineral compound with a molecular structure similar to graphene. While atoms within a single layer are strongly bonded, the bond between layers is weak, allowing them to be easily separated.

MoS2 nanolayers can be stacked in a solution and dehydrated to form the electrode-like device. The nanolayers expand and contract as ions are added and removed, creating a muscle-like effect and exerting a surface force.

Researchers detailed the technology this week in the journal Nature.

"The next step is to scale up and try to make actuators that can move bigger things," Chhowalla said.

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