Progress 09/01/23 to 08/31/24

Outputs
Target Audience:PLANT SCIENTISTS - research efforts and progress on developing the small-crop microtensiometer sensor was communicated to scientists regularly through our mailing list. We also had strong and ongoing collaboration with professors at UC Davis, U of Arizona, Cornell and others. GROWERS - initial field testing of the sensors was performed by growers of various crops. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?FloraPulse sends out a monthly mailing list that goes over our recent research accomplishments. This email goes out to researchers and growers worldwide. We also presented results at the Lab-Ferrer workshop in Spain (February 5, 2024) and the IFTA conference in Yakima, WA (February 11, 2024). What do you plan to do during the next reporting period to accomplish the goals?Goal #1 We did the groundwork for Goal #1 by developing the microfab plan, ordering the parts, and making new photolith masks. We also performed a fabrication to build chips for this phase of testing. During the next reporting period, we plan to test a new SiO2 photolithography mask that we believe could dramatically speed up the sensor response time. With a faster sensor, it becomes possible to increase the sensitivity by thinning out the sensing diaphragm. The microfab will further be fine-tuned in numerous ways to increase yield and decrease manufacture time. Goals #2 and #3. Progress on Goals #2 and #3, to develop and test the sensor installation for small crops, has been phenomenal. We've shown that sensors can measure water potential in small crops such as blueberry, cotton and grapes. The installation method is relatively straightforward and we've created videos on how to install sensors. Work on these goals will continue nonetheless, in particular to continue improving the sensor's reliability and ease of use. More testing and development is definitely needed to make our sensors work reliably in avocado and walnut, for instance. We also plan to test sensors in other crops, such as corn and tomatoes. Tasks to be done for goal #2 and #3: Design and test new installation hardware and tools Tweak and improve the installation method for: small crops, thick-bark crops and walnut/avocado (require a different install method to avoid the tree wounding response) Record updated installation videos, and write up instruction manuals Test updated sensor designs in field crops, FloraPulse and partners Improve sensor manufacture to increase yield and overall reliability Goal #4 Regarding goal #4, we will do the following: Continue development of the FloraPulse app and actually deploy it to our customers for testing Make small improvements to the datalogger and sensor electronics Engage with scientists to develop irrigation guidelines for each crop Record new versions of the installation videos.

Impacts
What was accomplished under these goals? Goal 1. Wafers were ordered and a step by step plan was developed. A new photolithography mask for SiO2 was designed and manufactured. Goal 2. Extensive methods were developed to test the probe prototypes. First, an artificial tree system was built and tested, then used to test probes. This system allowed measurement of the probe response time and propensity towards errors due to temperature or drying out. Second, we built a system to test sensor propensity to freeze under field conditions. We found that sensors can sometimes withstand temperatures down to -20C; this was an unexpected result. Third - we tried to build an osmotic test system, but determined that this setup was very difficult to do properly, and is not worth pursuing because the data is irrelevant to field conditions. Many iterations of installation hardware were manufactured and tested in the laboratory and field. We successfully built hardware that appears (so far) to work properly and reliably in the field trials started this year. The hardware has been made significantly easier to use over time, but this effort is still ongoing. Multiple mating compound formulations were tested and we picked a 'winning' formulation. A standard operating procedure was written to reliably make this mating compound. We found that a combination of kaolin clay and DI water works best. Sensor manufacture has been improved, which led to better sensor reliability and re-usability. At the moment, an estimated 90% of all tries at re-using a sensor are successful. Goal 3. The small sensors were tested by our partners in the following crops: avocado, blueberry, cherry, orange, grape, hazelnut, kiwi, prune and walnut. Results in all these crops were positive, but there were reliability issues, in particular with walnut and avocado. Research and improvements are ongoing. Goal 4. The FloraPulse smartphone app has gone through multiple iterations and we have a barebones app that shows the data and recommended levels. We recorded videos on how to install the small sensor version into small crops and into thick-bark trees.

Publications