Biodegradable Soil Sensors
The objective of the SEED project is to develop a biodegradable soil sensing device to measure infield conditions such as moisture, salinity, nitrogen, phosphorous, potassium and pH-levels in real time. The sensor should be approximately the same size as a seed and deployable during the planting process. The sensor shall degrade at the end of each planting season and leave no harmful toxins in the soil.
Soil sampling is an important tool in modern agriculture to ensure optimal plant growth and crop yield. Traditional methods of sampling require soil samples be sent to external laboratories for analysis. Due to ever changing field conditions, this lag in information can significantly impact plant health. Modern advances in soil sampling have seen a trend toward electronic infield monitoring of field conditions. However, with the introduction of electronics, the price and potential to contaminate the soil has increased. In an effort to reduce costs and potential harmful side effects, NDSU is partnering with industry leaders to develop a biodegradable soil sensor called SEED (Sensing Earth Environments Directly).
The current research for SEED focuses on the feedback mechanism. Given size restrictions and toxin concerns, passive RFID (Radio-Frequency Identification) tags are the logical choice to relay information to the farmer. Advances in modern manufacturing techniques allow the use of Micro Cold Spray to print RFID tags on biodegradable printed circuit boards (BPCBs).
The current primary focus of the Composites group at NDSU is on the BPCB. As typical with all circuit boards, flexibility, strength, and conductivity are vital to the BPCB’s success. Due to North Dakota’s position as the number one flax producer in the United States, the BPCBs produced at NDSU are made of a polylactic acid (PLA) flax fiber composition.
To produce the PLA flax fiber composite, a woven flax fiber mat from Composites Evolution is used. This fiber is sandwich between thin sheets of PLA with a PLA power between layers. The composite is formed using a hot press. Testing with the PLA flax fiber composites is ongoing.