System for assessing a microbial characteristic within a growing medium and associated methods

Patent metadata

Field	Value
Publication number	US-12448599-B2
Application number	US-202217858302-A
Country	US
Kind code	B2
Filing date	Jul 6, 2022
Priority date	Jul 6, 2021
Publication date	Oct 21, 2025
Grant date	Oct 21, 2025

Abstract

Systems and methods for assessing a microbial characteristic within a growing medium. Such a system assesses one or more microbial characteristics, such as biomass and/or microbial activity, within a growing medium, such as soil. Electrical properties of a microbially degradable material in contact with the growing medium are measured. The measurements are used to determine the microbial characteristic(s) based at least partly on degradation of the microbially degradable material.

First claim

The invention claimed is:

1. A system for assessing a microbial characteristic within a growing medium, the system comprising:
a control sensor configured to be located in the growing medium and to measure electrical resistance of the growing medium while therein;
a sensing sensor configured to be located in the growing medium and to measure electrical impedance of a sensing element thereof while in the growing medium, wherein the sensing element comprises a microbially degradable material on a surface of a sensing electrode, and wherein contact of the sensing element with bacteria in the growing medium causes physical degradation of the microbially degradable material, and degradation of the microbially degradable material changes the impedance of the sensing element; and
a computer system comprising one or more processors that run one or more software programs configured to determine a characteristic of the bacteria in the growing medium based on a resistance of the growing medium and an impedance of the sensing element as measured by the control sensor and the sensing sensor.

2. The system of claim 1 , wherein the computer system is configured to receive measurements obtained by the control sensor and the sensing sensor simultaneously, analyze the measurements to determine a resistance of the growing medium and an impedance of the sensing element, determine a state of degradation of the sensing element based on the resistance of the growing medium and the impedance of the sensing element, and determine an amount of the bacteria in the growing medium based on the state of degradation.

3. The system of claim 1 , wherein the computer system is configured to receive multiple measurements obtained by the control and sensing sensors simultaneously over a time period, analyze the measurements to identify changes in the resistance of the growing medium and changes in the impedance of the sensing element over the time period, determine a rate of degradation of the sensing element over the time period based on the identified changes, and determine a rate of growth of the bacteria in the growing medium based on the rate of degradation.

4. The system of claim 1 , wherein each of the control sensor and the sensing sensor includes an array of interdigitated electrodes disposed on a substrate, wherein the array of the control sensor is configured to contact the growing medium, and the array of the sensing sensor comprises a coating thereon configured to contact the growing medium, and wherein the coating comprises a film formed of the microbially degradable material.

5. The system of claim 1 , wherein the physical degradation caused by contact of the sensing element with bacteria includes the formation of pores on the surface of the sensing element, wherein the pores result in a decrease in differential impedance of the sensing element.

6. The system of claim 1 , wherein the microbially degradable material of the sensing element is formed of a cellulose material.

7. The system of claim 6 , wherein the cellulose material comprises cellulose acetate, chitin, lignin, or a combination thereof.

8. The system of claim 1 , wherein the bacteria are Pseudomonas aeruginosa.

9. The system of claim 1 , wherein the microbial characteristic comprises at least one of biomass and microbial activity.

10. A method of fabricating a sensing element of a sensing sensor for assessing a microbial characteristic in a growing medium, the sensing sensor being configured to be located in the growing medium and to measure electrical impedance while in the growing medium, the method comprising:
forming a sensor electrode comprising an array of exposed, interdigitated electrodes on a substrate;
coating the array on the substrate with a microbially degradable solution; and
curing the solution to form a microbially degradable film on the array.

11. The method of claim 10 , further comprising:
performing a pretreatment process on the array prior to coating the array with the solution, wherein the pretreatment process includes:
performing an initial plasma treatment of the sensor electrode;
performing an APTES treatment on the initially plasma treated sensor electrode by submerging the array in a solution of 3-Aminopropyltriethoxysilane (APTES); and
performing a secondary plasma treatment of the APTES treated sensor electrode.

12. The method of claim 10 , wherein the microbially degradable solution comprises a cellulose acetate (CA) solution.

13. The method of claim 12 wherein the step of coating comprises drop casting the CA solution on the array.

14. A method of assessing a microbial characteristic in a growing medium, the method comprising:
locating a control sensor in the growing medium, wherein the control sensor is configured to generate measurements of electrical resistance of the growing medium;
locating a sensing sensor in the growing medium, wherein the sensing sensor comprises a sensing element comprising a sensing electrode configured to generate measurements of electrical impedance and a film of microbially degradable material on the surface of the sensing electrode, wherein degradation of the film changes impedance of the sensing element, and wherein contact of the sensing element with bacteria in the growing medium causes physical degradation of the microbially degradable material;
receiving measurements of electrical resistance of the growing medium and measurements of electrical impedance obtained from the control sensor and the sensing sensor simultaneously while located in the growing medium;
analyzing the measurements to determine the resistance of the growing medium and the impedance of the sensing element; and
determining a characteristic of bacteria in the growing medium based on the resistance of the growing medium and the impedance of the sensing element.

15. The method of claim 14 , wherein the step of determining a characteristic comprises:
determining a state of degradation of the sensing element based on the resistance of the growing medium and the impedance of the sensing element; and
determining an amount of the bacteria in the growing medium based on the state of degradation.

16. The method of claim 14 , wherein the step of determining a characteristic comprises:
receiving multiple measurements obtained by each of the control sensor and the sensing sensor simultaneously over a time period;
analyzing the measurements to identify changes in the resistance of the growing medium and changes in the impedance of the sensing element over the time period;
determining a rate of degradation of the sensing element over the time period based on the identified changes in resistance and changes in impedance; and
determining a rate of growth of the bacteria in the growing medium based on the rate of degradation.

17. The method of claim 14 , wherein each of the control sensor and the sensing sensor comprises an array of interdigitated electrodes on a substrate, wherein locating the control sensor and the sensing sensor in the growing medium includes locating the control sensor in the growing medium such that the array of the control sensor contacts the growing medium and locating the sensing sensor in the growing medium such that the film on the array of the sensing sensor contacts the growing medium.

18. The method of claim 14 , further comprising measuring a decrease in differential impedance of the sensing element resulting from the formation of pores on the surface of the sensing element due to the physical degradation of the film caused by contact of the sens

Assignees

• Purdue Research Foundation

Inventors

• Rahimi Rahim
• Waimin Jose

Classifications

• C12M41/32

  of substances in solution · CPC title

• G01N33/0031

  comprising two or more sensors, e.g. a sensor array · CPC title

• G01N33/48735 Primary

  Investigating suspensions of cells, e.g. measuring microbe concentration (by chemical means C12Q1/04; colony counters C12M1/34; concentration of particle suspensions in general G01N15/06) · CPC title

• G01N27/02

  by investigating impedance · CPC title

• C12M41/46

  of cellular or enzymatic activity or functionality, e.g. cell viability · CPC title