The document discusses electronic sensors to detect impurities in water. It describes different methods under research to detect bacteria and viruses, including using changes in resonant frequency, capacitance, and gas signatures to detect E.coli. Detection using resonant frequency involves measuring changes in the oscillating frequency of a piezoelectric surface as E.coli accumulates on antibodies. Detection using capacitance measures changes in capacitance as E.coli sticks to antibody-coated capacitor plates. Gas signature detection analyzes unique gases emitted by E.coli using a gas sensor and neural network. Commercially available sensors include a pathogen detection system that detects E.coli in 4-18 hours and various test kits and filters.

1. Electronic Sensors to detect impurities in water

2. Objectives Selection of a Parameter used to check the presence of pathogens in water Different methods (under research) to detect the presence and amount of bacteria and virus in water Glimpse on sensors available in market to detect and filter pathogens

3. Need of a parameter to test pathogens Disease causing pathogens cannot be tested directly Because, They are Difficult to isolate and identify Cost of analysis Length of time to analyze With all the analysis presence of only one substance will be known Most of the labs use E.coli as a parameter to test pathogens present in water because It is easy to collect and test, Presence and Concentration Relatively harmless to environment If more fecal coliform populations present in water, the greater likelihood that pathogens are present

4. Research in the field of testing E.coli The well established lab method is To collect the sample of water to place the water in agar ( Nutrient environment for E.coli to grow) for some hours Test the rate of growth and compare The main disadvantage with this method is Time consumption So the recent research is to develop a handheld device to detect the presence of coli within few minutes as its presence can detect the following disease causing pathogens sore throats diarrhea abdominal cramps hepatitis respiratory infections chest pains

5. Detection of E.coli using resonant frequency Method1: (under research) Parameter Used : Change in resonating frequency Principle Used : The oscillating frequency of a substance changes when the bacteria gets accumulated on its surface. Expected time (as specified) : 10 min Layer containing Antibodies of E.coli Voltage source Slither of Glass Piezoelectric surface

6. Working Anti bodies present in glass will attract the E.coli if present in water As Alternating voltage is applied to the piezoelectric substance it will contract and expand making the glass slither to resonate Depending upon the amount of E.coli attached to the antibodies the resonating frequency of glass varies Using a sensor to detect the frequency variation, the amount of E.coli present can be analyzed

7. Detection of E.coli using capacitance Parameter Used: Variation in the capacitance Principle used : “ The capacitance of the capacitor is changed when the material between the capacitor plates changes” Expected Time to detect : within 30 min

8. Working At first Dummy capacitor is given a slightly higher value than sense capacitor in such way that Sense amplifier gives high voltage (saying False) The plates of sense capacitors is layered with antibodies of E.coli or nutrient media, So if immersed in water E.coli or viruses get stick to it. This infact changes the capacitor value and the sense amplifier now gives low voltage (saying true for presence of E.coli)

9. Detection of E.coli using Gas signatures Principle used : “ When the sample water is placed in nutrient broth, the gas emitted by E. coli O157:H7 is unique and can be captured by gas sensor” Block used: Gas sensor Artificial Neural Network Working: The signature of the E.coli is predicted already and neural network is trained for its gas patterns. Now the sample is placed in the nutrient broth . A gas sensor is used to detect the gas and neural network compares it with already available pattern. Gas from water

10. Sensors available in market Pathogen detection systems (Canada based company) developed a complete testing unit for detecting E.coli ( software included) Takes nearly 4-18 hrs to detect Snapshot of digital recorded results Sample holder with nutrient medium Full desktop testing unit

11. Sensing kits and filters available in market Filter to remove some bacteria and virus Test bottle to detect E.coli 23$ Self testing kit for bacteria detection 15$ Sensor or filters Company

12. Sensors and kits available in market Bacteria testing kit $9.95 Portable Bacteria sampler Kits and sensors Company Burk yard Scientific equipment