UHasselt Develops Smart Sensors That Grow With Pears

Researchers at Hasselt University (UHasselt) and the Proefcentrum Fruitteelt (pcfruit) in Belgium have developed stretchable sensors that can grow with pears and continuously monitor their development.

The technology could help fruit growers determine earlier which pears are likely to develop into high-quality fruit while also detecting heat stress before it causes serious problems.

The sensors are made using Galinstan, a liquid metal alloy consisting of gallium, indium and tin. A conductive track made from the material is embedded in flexible silicone, allowing the sensor to stretch as the pear grows.

As the sensor stretches, its electrical resistance changes. This allows it to continuously measure the thickness of the pear and provide growers with detailed information about its growth.

The technology could also make it easier for growers to thin pear trees more efficiently. Pears grow in clusters, but trees naturally shed some fruit during the growing season. Identifying those fruits early allows growers to remove them sooner, giving the remaining pears more space to develop.

“Growers can then thin the fruit themselves earlier, so the pears that remain can become better quality,” professor Wim Deferme explained. Instead of measuring fruit manually, growers could use the sensors to collect the information much more efficiently.

The sensors could also help determine when pears have reached full maturity. Growers would know more precisely when the fruit is ready to harvest and could adjust water and nutrient levels accordingly. The technology can also detect heat stress, allowing growers to provide additional water more quickly when needed.

The data collected by the sensors is analyzed using chips, with researchers hoping to better understand what happens during the fruit’s growth cycle and eventually make more accurate predictions.

“In the ideal scenario, all that data will eventually be sent to an app,” said researcher Thijs Vandenryt, who is involved in the project. “That would give the grower a clear overview of the current situation along with a number of predictions — a kind of weather radar for fruit growing.”

The researchers aim to bring the complete system to market within five years. However, several challenges remain, including making sure the sensors can withstand changing weather conditions and improving the efficiency of the manufacturing process.

Researchers also need to determine whether wearing the sensor has any effect on the fruit itself.

The sensors were tested this season in an orchard in Sint-Truiden, Belgium, and the harvested pears are now being analyzed. A separate project in Italy is testing the technology on apples.

The researchers are also exploring applications for other types of fruit, including coconuts and dragon fruit.