Underground soil moisture sensors “make in Vietnam” by Humans of HUST

Women's Day became much more meaningful at Hanoi University of Science and Technology thanks to the joyful news from Associate Professor Le Minh Thuy, a senior lecturer at the School of Electrical and Electronic Engineering. Associate Professor Le Minh Thuy won the 2023 Asian Innovation Award from the Global Hitachi Fund for her “greenes research”: Greenes: Greening the Future by Energy Harvesting Solutions from Ambient Sources. Her greenes solutions allow powering battery-less electronic devices by harvesting energy from various waste energy sources in our environment, including electromagnetic waves (GSM/3G/4G/5G/Wi-Fi), solar, triboelectric, and thermal electricity. This is the main idea of her research on the development of a self-powered underground soil moisture wireless sensor for precision agriculture. She often jokingly refers to her students, especially female students, as "The girls in the ground!”

The big idea stems from real-life

Soil moisture-based irrigation systems play a crucial role in precise agriculture. It directly affects the growth and productivity of crops. Both excess and insufficient water will interrupt the healthy growth of the plants.

Many types of soil moisture sensors are available on the market nowadays, but none are Made in Vietnam. Cheap sensors often have low quality and inaccurate measurements, while reliable sensors are relatively expensive.

Once during a seminar, an expert from the Vietnam National University of Agriculture shared with Associate Professor Le Minh Thuy: "If we bury many sensors in the ground, the total cost is high and power supply solution is a big challenge. If we bury the sensor manually, we will have to go to the field several times a day to insert temperature and soil moisture meters ourselves and to collect information. This job is very laborious, and sometimes the collected information is inaccurate, affecting research on crop quality."

"If there were a wireless device that could accurately measure the soil moisture content with a low cost and be able to instantly transmit information to a computer or smartphone, it would be fantastic. Such devices exist on the market, but they are too expensive, and on the other hand, cheap products’ reliability is questionable" the agricultural expert said to her. At the same time, the technical leader of a Vietnamese company operating in the field of agriculture shared his concerns about finding a low-cost sensing device that provides accurate information to make decisions about watering the flowers that he is currently interested in.

Knowing that Associate Professor Thuy’s expertise is smart sensing devices and ambient energy harvesting, she has been given a very specific assignment: improving cheap sensors (available on the market), solving environmental problems (to bury in the ground and can be discarded if no longer needed), and deploying on a large scale, with acceptable reliability.

From the sharing of agricultural experts, referencing many documents, and understanding the practical situation in Vietnam, Associate Professor Le Minh Thuy decided to research transmitting energy to the devices buried underground to lengthen the lifetime of the sensors.

She proposed the solution for an energy harvesting system integrated into a mobile robot to simultaneously transmit energy, collect soil moisture information, and upload it to the server. If successful, this would be a potential solution for the problem of flexible communication networks and power supply for underground devices.

This idea of Associate Professor Le Minh Thuy was awarded the 2023 Hitachi Global Innovation Award, an idea for green research shaping the future!

1 problem, 3 research directions!

To solve the problem, Associate Professor Le Minh Thuy proposed three basic, yet practical and specific research directions:

1.     Improving existing cheap sensors on the market. Use Advanced Machine Learning to enhance the accuracy of low-cost sensors known as Tiny Machine Learning.

2.     Developing a low-cost sensing device while ensuring reliability.

3.     Addressing the environmental challenge of burying devices in the soil, the goal is to develop disposable units that eliminate the need for excavation. To tackle this issue, the research team has completed two phases of their work and is now focused on integrating these components into a single, compact device. Research on soil moisture sensors has emerged since the 2010s, with the most contribution from American scientists. From 2020 onwards, French experts have also begun to delve into this area of study.

Currently, research groups from the US, UK, Japan, France, etc., have only reached the laboratory stage without fully implementing their product for practical use. This is the reason why Associate Professor Le Minh Thuy collaborated with Australian and British scientists on her research. Feedback from professors in the same field will help improve the product of Hanoi University of Science and Technology.

According to Associate Professor Thuy, scientists from the University of Nebraska-Lincoln, USA, are trying to address the problem of energy consumption. Currently, soil moisture sensors rely on either solar power, which depends on the climate; or batteries, which need to be dug up after a period for replacement.

"Regardless of how good the batteries are, their operational time is limited, and lifting them for maintenance is very inefficient. Currently, data collection is conducted using unmanned aerial vehicles to gather information and then upload it online. This solution is difficult to implement for wireless charging of sensors," explained Associate Professor Le Minh Thuy.

Associate Professor Le Minh Thuy and her students are conducting research based on the idea of using mobile robots to push carts through the places where moisture sensors are buried. Each time robots collect data, they transmit energy to the sensors while charging and gathering information from electromagnetic waves. The challenge is how to efficiently harvest energy and transmit information even when there is misalignment between the transmitter and receiver.

Associate Professor Thuy's research team has solved the misalignment problem of wireless power transfer systems for underground devices and now is conducting research on the integration of the information transmission block along with the power source, producing a compact product.

"This is the later phase of our research. I want to implement it in Vietnam and have a tangible product to 'test run'. At that time, it will require investment not only in human resources but also in financial support." Associate Professor Thuy said.

Agricultural experts and businesses are eagerly awaiting the finished product of the Made in Vietnam soil moisture sensor.

Meanwhile, the scientists of Hanoi University of Science and Technology - Associate Professor Le Minh Thuy and her colleagues - are racing at full throttle after announcing their scientific research internationally to have a low-cost, high-precision soil moisture measurement device in five years. The girls in the soil moisture team

Throughout her sharing about green research, Associate Professor Le Minh Thuy spends much time recounting the journey of the girls who have chosen to pursue fundamental research with her. They are the intelligent and talented students hailing from the 64th and 65th cohorts of the Control Engineering and Automation, School of Electrical and Electronic Engineering, Hanoi University of Science and Technology: Dinh Bao Ngan, Nguyen Thi Phuong Thao (cohort 64); Dao Phuong Thao, Do Thu Giang (cohort 65).
Associate Professor Thuy passionately details the "destiny" of how she and her students embarked on the scientific journey together. The "bonding formula" all stems from love, admiration, and mutual dedication.

Dinh Bao Ngan has just graduated from Hanoi University of Science and Technology. She has been offered a full-time salary by Viettel Group before her graduation. The two K65 female students, Phuong Thao, and Thu Giang, are pursuing their internship in France at the laboratory where Associate Professor Thuy worked formerly. "The students are following the path I pursued in the past. With their intelligence and excellence, they will undoubtedly have a bright future!" exclaimed Associate Professor Le Minh Thuy.

The appreciation and trust that Associate Professor Le Minh Thuy gives to her students stems from her own experiences in pursuing scientific research. Pursuing a research path requires patience and determination.

She often shares her feelings and thoughts with students about why she pursues scientific research to the end: “Sometimes I feel bored! When I want to quit, I ask myself why I started. If I think about that reason and still want to quit, then… quit, no regrets! But usually, thinking about the reason I started inspires me to keep trying!”.

Her passion, knowledge, and experience inspire students to study and research; the youth, dynamism, and creativity of the students are a source of inspiration for her to have more energy every day, as shared by Associate Professor Thuy: “I am fortunate to have learned many good things from my teachers. I hope to inspire and positively influence my students just as my teachers did for me!”. In supporting the team to achieve the current results, Associate Professor Le Minh Thuy has received a lot of help from “hidden” experts.

Associate Professor Thuy’s husband, who is also her colleague in the same laboratory at the School of Electrical and Electronic Engineering - Associate Professor Nguyen Quoc Cuong, is introduced by Associate Professor Thuy as her “spiritual leader”: “If it weren’t for him, I wouldn’t be here today!”

All of Associate Professor Thuy’s research ideas are first debated by Associate Professor Cuong. He is also the person who implements the research direction of applying machine learning in existing sensors to improve accuracy.

The research team is also supported by Associate Professor Nguyen Thanh Tung - the Deputy Director of the Institute of Materials, Vietnam Academy of Science and Technology in the manufacture of materials for wireless communication blocks; Dr. Nguyen Dai Duong – lecturer at School of Electrical and Electronic Engineering, HUST, and Dr. Ha Van Nam, who was formerly a student in Telecommunication and Electronic Engineering, Hanoi University of Science and Technology, and currently is a researcher at Aalto University, Finland, in research on energy harvesting and robots.

Talking about the “hidden” experts who help the research team, Associate Professor Le Minh Thuy always says she is lucky.
Associate Professor Thuy’s research has been supported scientifically by the APEC Fund (Australian Government’s Research Scholarship Program for female candidates from APEC member economies (Australia-APEC Women in Research Fellowship) since 2022. At the beginning of 2023, Associate Professor Thuy went to Australia as a visiting professor to collaborate with a group of professors at the University of Sydney. Soon, Mrs. Thuy will connect with a similar research group from Northumbria University, UK.

The scientific research of teachers and students at Hanoi University of Science and Technology has been published in international specialized journals, with a citation index (Impact Factor 7.8). International experts highly appreciate the idea of Hanoi University of Science and Technology’s lecturer.
 

“LOOKING FORWARD TO COLLABORATING ON RESEARCH” "The research topic of Associate Professor Le Minh Thuy is very interesting. The application of self-powered wireless underground sensor networks for precision agriculture is a potential solution for smart agriculture. The research results that Associate Professor Thuy sent to APEC are useful and deserve to be funded. She has visited our Technology Laboratories, connecting with many scholars. We hope that the future collaboration between Associate Professor Le Minh Thuy - Hanoi University of Technology and the University of Technology Sydney will further promote this green future research." Professor Eryk Dutkiewicz and Professor Diep Nguyen - University of Technology Sydney, Australia.