Method to sense the presence and activity of microbes through the use of transient sensing materials
Disclosed are sensors and related methods for measuring enzyme activity in a measurement environment and for quantifying enzyme and/or microbe concentrations in the measurement environment. An enzyme activity sensor includes a degradable conductive trace and a biodegradable target configured to enable the conductive trace, in an initial state, to conduct electrical current between first and second terminal ends via conductive particles. The conductive trace is configured to degrade over time as a result of enzymatic activity that degrades the biodegradable target when the sensor is placed in a measurement environment, the enzymatic activity thereby increasing resistance between the first and second terminal ends.
1. A sensor configured for measuring enzyme activity corresponding to true in situ enzyme activity levels, the sensor comprising:
a degradable conductive trace that includes
a first terminal end, a second terminal end, and an intermediate section disposed between the first and second terminal ends, the intermediate section including conductive particles disposed therein,
a biodegradable target configured to enable the conductive trace, in an initial state, to conduct electrical current between the first and second terminal ends via the conductive particles, and
wherein at least the intermediate section is configured to degrade over time as a result of in situ enzymatic activity of a target microorganism or group of microorganisms that degrades the biodegradable target when the sensor is placed in a measurement environment, the enzymatic activity thereby increasing resistance between the first and second terminal ends,
wherein at least the intermediate section omits overlying layers such that the biodegradable target is directly exposed to the target microorganism or group of microorganisms when placed in the measurement environment; and
a support upon which the conductive trace is disposed.
2. The sensor of claim 1 , wherein the biodegradable target comprises a binder in which the conductive particles are disposed, the binder being formed from a biodegradable material that degrades over time when exposed to one or more enzymes that act upon the biodegradable material.
3. The sensor of claim 2 , wherein the binder is not water-soluble.
4. The sensor of claim 3 , wherein the binder includes an oligo- or polysaccharide and comprises one or more of cellulose, cellobiose, hemicellulose, cellulose derivative, xylooligosaccharide (XOS), fructooligosaccharide (FOS), galactooligosaccharide (GOS), isomaltooligosaccharide (IMO), inulin, chitin, chitosan, alginate, carrageenan, or starch-based polymer.
5. The sensor of claim 2 , wherein the binder absorbs water and swells when exposed thereto.
6. The sensor of claim 2 , wherein the binder comprises one or more of a lignin, oligo- or polysaccharide, wax, polyhydroxyalkanoate, fatty acid or fatty acid ester, alkane, polyester, copolyester, polyurethane, polyvinyl ester, or polyacrylate.
7. The sensor of claim 2 , wherein the binder includes a wax and comprises one or more of paraffin wax, beeswax, or soy wax.
8. The sensor of claim 2 , wherein the binder includes a fatty acid or ester thereof comprising palmitate.
9. The sensor of claim 2 , wherein the binder includes an alkane selected from nonacosane, hexadecane, or octadecane.
10. The sensor of claim 2 , wherein the binder includes a polyester and comprises one or more of polycaprolactone (PCL), polyethylene terephthalate (PET), polylactic acid (PLA), or polyglycolic acid (PGA).
11. The sensor of claim 2 , wherein the binder includes a polyvinyl ester and comprises one or both of polyvinyl acetate or polyvinyl propionate.
12. The sensor of claim 2 , wherein the binder includes a polyacrylate and comprises one or more of polymethyl acrylate, polyethyl acrylate, or polybutyl acrylate.
13. The sensor of claim 2 , wherein the binder includes a copolyester and comprises poly(butylene adipate-co-butylene furandicarboxylate).
14. The sensor of claim 2 , wherein the binder comprises one or more petroleum hydrocarbons.
15. The sensor of claim 2 , wherein the binder comprises one or more of cotton or paper.
16. The sensor of claim 1 , wherein the conductive particles comprise carbon particles.
17. The sensor of claim 1 , wherein the conductive particles comprise metal particles.
18. The sensor of claim 17 , wherein the conductive trace forms a “U” shape.
19. The sensor of claim 1 , wherein the conductive particles comprise tungsten, zinc, magnesium, or iron particles.
20. The sensor of claim 1 , wherein the conductive trace is positioned in a curved shape.
21. A system for measuring enzyme activity in a measurement environment, the system comprising one or more enzyme activity sensors as in claim 1 .
22. The system of claim 21 , wherein the system comprises an enzyme sensor panel comprising multiple different enzyme sensors configured to sense a different enzyme or combination of enzymes.
23. The system of claim 21 , further comprising a power source coupled to the one or more enzyme activity sensors.
24. The system of claim 23 , wherein the power source comprises a solar panel.
25. The system of claim 21 , further comprising a controller in electrical communication with the one or more enzyme activity sensors, the controller being configured to deliver electrical current to the one or more enzyme activity sensors and measure resulting resistance.
26. The system of claim 25 , further comprising a communications module communicatively connected to the controller and configured to connect to a network to enable transfer of sensor data and/or receipt of system instructions.
27. The system of claim 26 , wherein the network is a cellular network or a satellite network.
28. A method of measuring enzyme activity, the method comprising:
providing an enzyme activity sensor as in claim 1 , the biodegradable target of the enzyme activity sensor being configured to degrade in the presence of one or more target enzymes;
positioning the enzyme activity sensor in a measurement environment having or suspected of having the one or more target enzymes;
measuring resistance in the conductive trace of the enzyme activity sensor;
determining that the resistance has reached a threshold level indicative of enzymatic degradation of the biodegradable target of the enzyme activity sensor; and
based on the time to reach the threshold level indicative of enzymatic degradation of the biodegradable target, determine a level of the one or more target enzymes in the measurement environment.
29. The method of claim 28 , wherein the one or more target enzymes comprise cellobiohydrolase, β-glucosidase, β-xylosidase, phenol oxidase, peroxidase, chitinase, chitin deacetylase, urease, phosphatase, cutinase, PHB-depolymerase, lipase, lipolase, pancrease, xanthine oxidase, catalase, esterase, pullulanase, or amylase.