SUMMARY:
UCLA researchers in the department of Electrical Engineering have developed a lightweight portable optical device that can rapidly detect fecal coliform in contaminated drinking water on site with minimal training and equipment.
BACKGROUND:
According to the World Health Organization (WHO), 785 million people lack safe drinking water, and at least 2 billion people use water sources contaminated with feces. It’s estimated that 1 million people die every year due to water, sanitation or hygiene related problems, and every 2 minutes a child dies due to poor quality water.
Water can contain hundreds of different microorganisms, making the analysis of all possible pathogenic microorganisms very challenging. However, the presence of E. coli and total coliform in a water sample is widely accepted as evidence for contamination of a water supply. There are several EPA-approved methods used to monitor water quality which employ conventional microbiological techniques. However, these microbiological methods have some limitations, such as a long total analysis time, interference from non-coliform bacteria, limited detection of slow growing or stressed coliform, viable but non-culturable (VBNC) bacteria, and requiring transportation to central lab facilities with trained professionals. Water quality can also be monitored by optical, electrochemical, piezoelectric or plasmonic biosensors. However, such biosensor technologies typically lack sensitivity and/or are constrained to very small sample volumes, in addition to requiring complex and expensive benchtop equipment to operate.
One of the EPA-approved methods for E. coli and total coliform detection is Colilert. This is one of the most widely used techniques and is used to simultaneously detect E. coli and total coliform in drinking water by changing the color of contaminated water to yellow. However, the Colilert process takes 24 to 28 hours, and is not an on-site method.
There is a clear need for an on-site device that can operated without specialized personnel that is capable of detecting 1 CFU/100 mL in less than 24 hours.
INNOVATION:
Researchers at UCLA have developed a small, automated optical device that uses Colilert to rapidly detect bacterial contamination. The device performs periodic measurements of the absorption and fluorescence of water. Images are digitally processed to detect the presence of bacteria in each well of a well plate. Tests demonstrated that this 1.66-kg device can automatically detect the presence of both E. coli and total coliform within ~16 hours, down to a level of one colony-forming unit (CFU) per 100 mL, which allows the sample to be processed on site, using limited laboratory equipment and without specialized personnel.
POTENTIAL APPLICATIONS:
- Water Contamination Testing
- On-Site Colorimetric Testing
ADVANTAGES:
- On-Site
- Minimal Training
- Rapid Detection
- Light Weight
- Sensitive
DEVELOPMENT-TO-DATE:
A prototype device has been developed and tested to show high sensitivity of detection of contaminated water samples within 16 hours.
Related Papers:
Tok, S., de Haan, K., Tseng, D., Usanmaz, C. F., Ceylan Koydemir, H., & Ozcan, A. (2019). Early detection of E. coli and total coliform using an automated, colorimetric and fluorometric fiber optics-based device. Lab on a chip, 19(17), 2925–2935.