After building the NPK sensors and talking with farmers about their sensor needs and feelings toward biosensors, we brainstormed creative applications for our system of genetic circuits.
At its inception, the goal of this project was to design a method of determining macronutrient concentrations that was cheap, simple, and easy to use for farmers around the world. However, when we did research on what products were currently available to sense soil macronutrient concentrations, we concluded that many satisfactory low-cost chemical assays have already been developed.
We decided to explore where the current NPK tests could be improved, so we established the most important criteria for a sensor design. A good sensor for this application is accurate, easy to use, low cost, gives a quick readout of the results, and is composed of relatively stable components. We then identified two common chemical assays, a colorimetric at-home-kit and laboratory tests, and compared them in each of our design criteria categories in a simple Pugh Matrix (Table 1).
insert pugh matrix
Our analysis showed that, while many of these assays provide cheap and rapid measurement of NPK levels, they do so at the cost of accuracy. We designed the biosensors to be useful parts for many future applications and did not design them to specifically improve accuracy. However, we would still like to test if the biological rather than purely chemical basis of our circuits enables them to get a more accurate reading of what nutrients are readily available from the perspective of a growing plant (hopefully a source).
Considering the accessibility of chemical NPK assays and public opinion toward biosensors, we have begun developing two separate applications of the NPK sensors: a paper-based lysate and a controlled biofertilizer system.
PUGH MATRIX goes here
Paper-based Lysate
We want to deploy our sensors in a way that would alleviate biosafety concerns, continue to be quick and low-cost so that it continues to be competitive with current products, but also includes the accuracy that comes with being a biological circuit (source hopefully). With these criteria in mind, we decided to make a paper-based testing assay.
Motivated by a paper-based lysate
Collins paper: https://owlspace-ccm.rice.edu/access/content/group/8f11257d-cfeb-4071-9a1a-7aeb99995e5a/Background%20Papers/Paper-based%20synthetic%20gene%20networks.pdf