Phytoelectronic soil sensing

Lead Research Organisation: University of Cambridge
Department Name: Engineering

Abstract

The research objective of this project is to accurately, densely and remotely measure the state of the soil using plants as in situ chemical laboratories. The sap of these "interrogator plants" will be analyzed by implanted bioelectronic sensors and remotely communicated by low-power radio interrogation. This approach will avoid the complexity of sensing the soil directly by instead detecting the chemical response of vascular fluids to chemical and biological changes of the soil around the roots. These fluids, which are transported by the woody xylem tissues, are under negative pressure and thus typically difficult to access. The project will thus investigate a number of regeneration techniques for surgically implanted, small sensors such that these sensors become grafted into the xylem tissue, much like fruit trees are currently grafted. The entire small sensor including implanted electronics and regenerative coating will be screen-printed for very low cost. Screen printing recipes and other enabling techniques will be shared with the public through the Open Science Framework. Public use of these results will be further fostered by funded kits distributed to teams through the international BioMaker and OpenPlant programs.

Planned Impact

Disadvantaged Colorado high school students will explore the integration of phytoelectronic sensors and Arduinos via massively online courseware created by the PI. Undergraduate Capstone students will contribute to the research by developing the custom RFID interrogator. Graduates will gain international research training by continuing the established exchange of students between the US and UK PI labs. Participation of under-represented groups will be increased by REUs of female physics students from a liberal arts school and the CU GoldShirt program for motivated and under-represented students.
Global dissemination of program results such as DIY screen-printing processes for phytoelectronic sensors will occur through the Open Science Framework. Public use of these results will be fostered by funded kits distributed to teams through the international BioMaker and OpenPlant programs. Researchers at the Forestry and Agricultural Biotechnology Institute, Pretoria will apply project results to permanent soil monitoring in woody plants. This project is expected to be the first of many promoted through a newly established Phytoelectronics Working Group with BioMaker partners at the Kumasi Hive in Ghana, Mansoura University, Egypt; University of Pretoria, South Africa; Bahir Dar University, Ethiopia and University of Adelaide, Australia.

Publications

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Bidinger S (2022) Highly stable PEDOT:PSS electrochemical transistors in Applied Physics Letters

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Han S (2021) Integration of Organic Electrochemical Transistors with Implantable Probes in Advanced Materials Technologies

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Han S (2020) Microfabricated Ion-Selective Transistors with Fast and Super-Nernstian Response. in Advanced materials (Deerfield Beach, Fla.)

 
Description Transistor-based ion sensors have evolved significantly, but the best-performing ones rely on a liquid electrolyte as an internal ion reservoir between the ion-selective membrane (ISM) and the channel. This liquid reservoir makes sensor miniaturization difficult and leads to devices that are bulky and have limited mechanical flexibility. We demonstrated microfabricated ion-selective organic electrochemical transistors (OECTs) with high performance (a transconductance of 4 mS), in which a thin polyelectrolyte film with mobile sodium ions replaces the liquid reservoir. These devices are capable of selective detection of various ions with a fast response time (~1 s), a super-Nernstian sensitivity (85 mV dec-1) and a high current sensitivity (224 µA dec-1), comparing favorably to other ion sensors based on traditional and emerging materials. Furthermore, the ion-selective OECTs are stable with highly reproducible sensitivity even after 5 months. These characteristics are well suited for applications in plants and also pave the way for new applications in a varierty of sectors beyond agricutlure.

We demonstrated exceptionally high stability in carefully prepared OECTs using commercially available PEDOT:PSS as the channel layer. These devices exhibit more than 99% retention of the baseline current over 50 transfer curve cycles and, importantly, after several changes of electrolyte solution. Furthermore, impressive stability is demonstrated during continuous measurements of the drain current. These results show that PEDOT:PSS OECTs are ready for biosensing applications requiring accurate continuous monitoring, such as the ones in sensing in plants and soil.
Exploitation Route Ion sensors are being used in many sectors and the fact that we have achieved in making them small and highly performant may lead to applications beyond the sector targeted in this grant. For example, they can be used in implantable formats to study the brain.
Sectors Aerospace, Defence and Marine,Agriculture, Food and Drink,Electronics,Environment,Healthcare,Manufacturing, including Industrial Biotechology

 
Description Scion Research 
Organisation Scion
Country New Zealand 
Sector Public 
PI Contribution We started a collaboration with Scion who are interested in using our sensors to monitor the health of forests in New Zealand. So far the collaboration has yielded a travel grant for the team of Prof. Malliaras to visit Scion, but no visits have taken place due to the COVID pandemic. A proposal to the government of NZ was submitted, to fund research in using the UCAM sensors in NZ
Collaborator Contribution The partners will help us expand the use of our sensors to monitoring the health of forests.
Impact A proposal was submitted to the governement of NZ
Start Year 2021
 
Description CDT-Sumitomo online workshop 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact UK-Japan online workshop to discuss advanced research topics and possible translation to applications
Year(s) Of Engagement Activity 2021
 
Description Creation and running of online training workshops for Biomaker 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact In response to the COVID lockdown Stephanie Norwood and I, as organisers of the Biomaker initiative, introduced more easily accessible hardware resources and created novel training materials for online teaching of no-code programming techniques for biologists lacking in formal programming skills. (https://www.biomaker.org/nocode-programming-for-biology-handbook). We have distributed around 200 hardware kits and run a series of online workshops via Zoom.
Year(s) Of Engagement Activity 2020,2021
URL https://www.biomaker.org
 
Description Invited presentation at CRI, Paris 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Invited presentation: Open Tools for Engineering Biology
Year(s) Of Engagement Activity 2021
 
Description Invited presentation at online Hitachi-sponsored workshop in Cambridge 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact UK-Japan online workshop to discuss advanced research projects and possible industrial translation.
Year(s) Of Engagement Activity 2021
 
Description Keynote presentation: "Hybrid and 3D Printed Bioelectronics" 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Third sector organisations
Results and Impact 11th International Conference & Exhibition on Green Flexible & Printed Electronics Industry
Held Oct 22, 2021 in Athens, Greece
Year(s) Of Engagement Activity 2021
 
Description No-code programming online workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Organised and delivered an online workshop to provide training for non-programmers in the use of microcontrollers for scientific applications. Distributed standard hardware for the training sessions ahead of the workshop. Dec 8th and 9th 2021.
Year(s) Of Engagement Activity 2021
URL https://www.biomaker.org
 
Description No-code programming workshop, University of Veracruz, Mexico 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Online workshop, co-sponsored with Prof. Mario Arteaga, University of Veracruz, Mexico - introducing research students to no-code programming for scientific instrumentation.
Year(s) Of Engagement Activity 2022
URL https://www.biomaker.org
 
Description Production and distribution of Biomaker training materials for online training. 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Provision of free online training materials to complement a starter pack is based on the Grove All-in-One Beginner Kit for Arduino. We have developed a visual guide, which provides step-by-step instructions of how to control the board using the XOD visual programming environment. The first lessons are available for download now. XOD tutorial code is also available to accompany this guide. In addition, training videos can be viewed online.
Year(s) Of Engagement Activity 2020,2021
URL https://www.biomaker.org/nocode-programming-for-biology-handbook