Recipient Organization
INTELLIGENT OPTICAL SYSTEMS, INC.
19601 MARINER AVE
TORRANCE,CA 90503
Performing Department
(N/A)
Non Technical Summary
Water is a finite resource, essential for all life on Earth. Monitoring water quality to determine the impact of contaminants from industrial, agriculture, stormwater, wastewater, and homes is important to improving and/or protecting the quantity and quality of natural resources.Typical field measurements (made directly in the stream, river, or lake) of water quality include dissolved oxygen, pH, temperature, and salinity, as these are usually the most common indicators of impairment. Nitrate and phosphate are critical for good crop growth in farming, but when they become too concentrated in our water they can cause serious environmental problems, so monitoring their levels in water is important to protecting natural water resources while also promoting sustainable agricultural production.Water quality is typically evaluated by taking a sample from the body of water, and then sending it to a laboratory for analysis. This method is time consuming, expensive, and does not give a full picture of what is happening over the entire body of water and around it. Another method is by fixed installation sensor stations, which continuously collect data and transmit it to a monitoring center or a web server. These types of sensors tend to be unstable and require regular maintenance. Other methods, such as color-indicating test strips and some portable sensors can give results at the source, but they are unreliable and not very accurate, and none are suitable for wide area monitoring. What is needed is an accurate, reliable, inexpensive way to collect real-time information on water quality over large areas.Over the past decade, unmanned aerial vehicles (more commonly referred to as "drones") have emerged as new and versatile tools for monitoring and assessing the natural environment. Drones equipped with chemical sensors are being recognized as valuable tools for monitoring air quality, but in water quality monitoring they are mostly used for water sampling and imaging. To our knowledge, there is no commercial drone-based sensing system on the market to collect chemical data from bodies of water directly at the source, mainly due to the small carrying capacity and power requirements of drones.In this project we will combine our proven miniature optical sensors and waterproof optical cable with a compact, lightweight reader, and mount the system on a commercially available drone. The drone will be flown out over a lake, where it will be directed to lower the sensing cable into the water and take measurements. A water sample collected from the same location at the same time will be analyzed in a laboratory to compare the measurements to those from the sensing cable.IOS has previously developed and matured optical sensors to measure pH, oxygen, and nitrate levels in water, all of which have been validated in field testing with groundwater. In this project, we will also develop a sensor film to detect phosphate. The sensor films are indicator molecules that react to a specific chemical (i.e., oxygen) and have been immobilized in a polymer film. These chemical-indicating films are small and lightweight, and can be cut or formed to any shape. All of the sensors will undergo testing to determine the effects of equilibrium time (how long the drone needs to stay at one testing location), flowrate, and temperature on their performance. We will design and 3D print a low-cost disposable sensor cartridge, which will hold all of the sensor films. The cartridge will be adapted to fit onto the waterproof optical cable. This allows the optical fibers in the cable to transmit light while being protected from the water, and the sensors in the cartridge to be directly exposed to the water. The information gathered by the sensors will be collected and stored by a compact luminescence readout device developed by IOS (small enough to easily fit onto a drone), and later transferred to a computer wirelessly or with a flash drive.The ultimate goal of this research is to deliver a reliable, rugged, accurate, and inexpensive water quality monitoring system that can be mounted on a drone to sample and test several variables in water, in real time and at the source. The use of a drone will allow multiple locations of a water body to be monitored, rather than just a single location as is done now with a typical water sampler. The ability to remotely access a waterbody will also dramatically reduce the cost of water quality monitoring, and enable significantly more effective monitoring and mitigation strategies in sustainable water management.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
100%
Goals / Objectives
The overall goal of this project is to demonstrate the feasibility of a drone-mounted sensing system that can remotely access a waterbody to collect in-situ hydro-chemical data, thus dramatically reducing the cost of water quality monitoring. The following specific objectives are planned:Objective 1. Demonstrate an optical sensor capable of detecting phosphate at concentrations relevant to biogeochemical monitoring.Objective 2. Characterize optical sensor performance under a realistic range of temperatures, flowrates, and air-water phases.Objective 3. Fabricate a drone-mounted sensing prototype, and perform a field test.
Project Methods
Although drones equipped with chemical sensors are emerging as valuable tools for monitoring air quality, current drone-based technology for monitoring water quality is still limited, with water sampling and detection based on photos taken by the drone. The proposed drone-mounted sensing system will create unique opportunities for remote water in-situ analysis.The overall concept will be to mount an optical readout unit to a drone platform, with optical fibers sealed in a rugged waterproof optical cable, and a disposable sensor cartridge containing multiple sensor films. The drone carries the optical reader, optical cable, and sensor cartridge to a specific location, where the sensor cartridge is submerged in water to collect physical-chemical information. A small ultrasonic sensor within the sensing system measures the distance between the drone and the water surface, so that the depth of the tested water can be calculated, since the length of released optical cable is controlled. Therefore, the proposed drone-mounted sensing system will record the location of the target analytes in the water body. The analyte testing results, GPS information, and testing depth will be stored on a microchip in the optical reader, from which it will be transferred to a computer wirelessly or with a flash drive.In Phase I, we will first develop and demonstrate an optical sensor capable of detecting phosphate at concentrations relevant to biogeochemical monitoring. Next, we will evaluate the analytical characteristics of optical sensors for pH, nitrate, and dissolved oxygen previously developed at IOS, as well as the newly developed phosphate optical sensor, under a realistic range of temperatures, flow rates, and air-water phases. Making use of our advanced 3D printing capabilities, we will design and fabricate a low-cost disposable sensor cartridge to hold the sensor films. The cartridge will be adapted to a waterproof optical cable containing multiple optical fiber tips, so that all the fibers that transmit light are well protected from the water environment, while the sensing films are directly exposed to the water for free exchange of liquids and dissolved gases between the water and the films. The optical fiber tips will transmit the optical signal between the sensor films and a compact phase-resolved luminescence detector readout unit (SeePhase) previously developed by IOS. Requiring no power and being a small payload on the drone, the SeePhase readout device is a perfect fit for the proposed drone-mounted sensing system (1.5 in x 4.3 in x 4.7 in; weighs 1.35 lb; internal battery can last for >3 hr; microchip for data storage). Finally, we will assemble a system demonstrator integrating the SeePhase unit and sensing cable with a drone, and after calibration and validation in the laboratory, will perform an initial field study by monitoring water quality of a lake. The purpose of this task is to demonstrate that the sensors can operate under field conditions; many promising sensor technologies show their limits when they are taken out of the laboratory and exercised in end user environments. The proposed drone-mounted water sensing system will be submerged in a lake to take measurements, and a water sample will be collected from the same location and sent out for laboratory analysis to validate its performance, though full validation of sensing system performance in the field by comparison with established analytical techniques will be deferred to Phase II.