Our sponsor creates and tests technology often used by survey companies. Currently, he is working on optimizing the performance of his existing ground sensors. GroundMetrics (GMI) has developed sensors that enable further improvements in recovery by monitoring the pumping process and identifying remaining oil. The GMI system involves deploying roughly two dozen or more sensors onto about 2,600,000 square meters of land. Placed alone, without a coupling bag, the eCube sensors experience a poor electrical connection with the soil and record poor data. When paired with a coupling bag, the eCube sensors capture accurate data and perform consistently until water runs low inside the coupling bag. In desert environments, the coupling bag retains adequate water for about one day before it has to be refilled with water. In the field, refilling the coupling bags means that hired technicians must refill each coupling bag with around sixty milliliters of water. In addition, the need for a water supply can also be a challenge in remote, desert-like territories. In many cases water is not readily available, and a water reserve must be shipped or carried into each specific environment. Overall, decreasing the water needs of the GMI system will in turn decrease water related costs.
High Priority Objectives
Maintain noise performance of less than 200 nV per hertz
Bags are 10-1000 ohms in resistance to the sensor
Bags conform to shape of the ground
Bags enabling low noise operation of sensors and staying moist for more than a day
Secondary Priority Objectives
Limit solar loading on exposed bag surfaces via shading structure
Integrate bag with the sensor if possible
Other Constraints and Issues
Reasonable conductivity (porous to water)
Material needs to resist static (not triboelectric)
The device has high sensitivity to vibrations and movement (ex. Water or wind)
Sensor needs to sit still under blowing wind (performance low noise issue)
WOW Design Solution
Lower maintenance needs (ex. Adding water)
No harmful or unsightly materials left behind
Electric conductivity between ground and material of bag
Bag lasting 7 days before having to re-add water
The bag stabilizes the sensor
Reduce/low moisture permeability
Shading of solar exposed areas of the bag
Mixed construction (different layers for top & sides vs. bottom layer of bag)
Change material properties to improve the design
Risk Reduction Objectives
Test different bag materials to find better water loss performance
Make sure that material for bag is durable yet conformable
Research materials online
Test water loss via a controlled test bed environment
Intermediate milestones
Choose 1-3 designs
Component analysis completed
Choose and purchase materials
Completion of the testing jig (sponsor created)
Create multiple bag compositions (different material layers)
Noise tested bag for less than 200 nV per hertz requirement
Created working controlled water loss test bed
Created Noryl shading structure prototype
Fabricated six to eight copies of final bag design
Individual Component Analysis Topics
Bag material
Liquid compound
Solar deflection/absorption structure/component
Reservoir structure