Announcements

The Sensors 2023 Best Ph.D. Thesis Award has been granted to the following thesis:

“Printed Organic Electronics for Plant and Environmental Monitoring”
by Elliot Strand, University of Colorado Boulder, USA

The following is an interview with Dr. Elliot Strand:

1. Can you briefly introduce the main research content of your Ph.D. thesis and its significance in the field of sensors? Additionally, could you share some emerging research directions in this field?
The core content of my thesis answers the following research question: How can we utilize printed organic electronics for plant health and environmental monitoring? Printed organic electronics is a field that combines organic chemistry with printing technologies to craft flexible and lightweight electronic devices. What really excites me about this area of study is its scalability. Unlike conventional electronics manufacturing, printing techniques eliminate the need for high-temperature and vacuum environments, making it a cost-effective and accessible solution for mass production.
There is a vast opportunity for future research and development in the field of printed organic electronics for agricultural and environmental monitoring. Since organic electrochemical transistors (OECTs) inherently operate in aqueous media and amplify biochemical signals, they are extremely relevant devices for detecting analytes that have relatively low concentrations in nature. Gate functionalization approaches, such as the deposition of gel-based membranes with immobilized markers and the incorporation of self-assembled monolayers (SAMs), are promising techniques to detect specific biomarkers based on electrochemical reactions at the gate electrode. Additionally, to avoid contributing to the global issue of electronic (e-) waste, considerable research should focus on developing printed devices that are environmentally friendly. In the case of biodegradability, the devices would operate for a set period and then naturally decompose into their environment after their service life. Since the substrate and encapsulant components make up most of the mass for a given printed electrochemical sensor, these constituents are a natural starting point. Plastic substrates could be replaced with compostable materials like cellulose or sugars, while natural waxes and rosins could be used as dielectric encapsulants.

2. What intriguing discoveries or unexpected breakthroughs did you discover during the research process? Please share some insights into these findings.
During my Ph.D. research, I discovered the transformative power that strategic device architecture considerations and simple additives have in enhancing printed sensor performance. In Chapter 4 of my thesis, I describe one notable breakthrough of incorporating a small amount of sugar alcohol into a commercially available screen printing ink. This seemingly minor addition exerted a significant influence on critical factors such as print thickness and the sensitivity of electrochemical transistors for detecting ionic nutrients. In another compelling finding detailed in Chapter 7, I experimented with the introduction of an additional encapsulation layer of ethyl cellulose over printed carbon electrodes. This relatively straightforward modification yielded a remarkable enhancement in the device's functionality, particularly for capacitive humidity sensing. What made these insights particularly exciting was the fact that each device was constructed mostly from commercially available ink materials; however, a subtle compositional change or innovative design approach could unlock previously untapped potential for the given sensor.

3. Could you describe some of the obstacles you encountered while conducting your Ph.D. research? How did you overcome them?
One of the most significant obstacles I encountered during graduate school was to develop the laboratory's screen printing process from the ground up. When I began my Ph.D., this challenge was daunting, given that no one at CU Boulder had previously manufactured a multi-layer electronic device solely through printing. I will never forget the initial guidance from my advisor, Dr. Gregory Whiting, to try hand-painting the different electronic ink materials to get a better understanding of their properties. I immediately purchased artist paint brushes from a local hardware store and was off to the races. Unsurprisingly, my first attempts yielded poorly performing devices. However, I persevered, gradually building my knowledge and incorporating techniques such as blade coating, laser cutting, and stencil application. These tools allowed me to establish a layer-by-layer alignment process, overcoming the initial setbacks. I take pride in the fact that screen printing is now widely utilized by most of the graduate students in the lab. This experience underscored the importance of persistence, innovative problem-solving, and relentless interaction during the research process.

4. When and how did you first become aware of the Sensors journal? What motivated you to apply for the Sensors 2023 Best Ph.D. Thesis Award?
Throughout my time in graduate school, our research group had an established collaboration with a similarly themed lab at the University of California, Berkeley. A few of our collaborators from this partnership published an exciting paper in Sensors that focused on screen-printed potentiometric sensors for monitoring nitrate in soils. In particular, my colleague, Dr. Payton Goodrich, who played a pivotal role in the publication, introduced me to the journal and encouraged me to apply for the prestigious Best Ph.D. Thesis Award.

5. How has the Sensors 2023 Best Ph.D. Thesis Award helped to support the career of a young/early career researcher? What advice do you have for aspiring young researchers like yourself?
The Sensors 2023 Best Ph.D. Thesis Award boosts the career of a young researcher by offering recognition and validation of their academic contributions, enhancing visibility within the scientific community, and establishing credibility that opens doors to collaboration and funding.
My advice for aspiring young researchers is to embrace failure as a crucial part of the learning process. Regular attendance and consistent prioritization are key; showing up and dedicating time to high-priority tasks will lead to the creation of new knowledge. Don’t forget that the opportunity to contribute to the advancement of knowledge is a privilege, and perseverance through challenges is an integral aspect of the journey.

6. How do you plan to advance and expand upon your research in the future, and what are your long-term career aspirations in the field of sensors and beyond?
Dr. Payton Goodrich, my colleague from UC Berkeley, and I have recently co-founded a startup. Our goal is to leverage the printed sensor technology that we developed during our Ph.D. research to create the product. This product is intended to assist growers, regulators, consultants, and municipalities in enhancing the efficiency, sustainability, and profitability of their operations. If you want to learn more, feel free to connect with us.
Looking torwards the future, my long-term career aspirations revolve around providing both broad and local service. With a passion for sustainability, I am dedicated to improving our species' interaction with nature and promoting sustainable practices in every industry that I can. Furthermore, I aspire to contribute to my community by educating and empowering the next generation of STEM leaders to excel in their fields, innovate solutions to global challenges, and positively impact the world through their scientific knowledge and quality leadership.