Melamine is a compound generally used in manufacturing a type of plastic (melamine-formaldehyde) resin. Due to its high nitrogen content, melamine can increase the apparent protein content of food substances, especially milk, making it a widely used adulterant. The adulteration was at its peak in 2008 when, in China, close to 300,000 victims, mostly infants, suffered due to milk and an infant formula that had been adulterated with melamine. An excess of melamine in the body could lead to kidney stones and other renal problems.
?We have built a device that uses nanotechnology to detect melamine in milk,? said S. Varun, the lead researcher at the Optics and Microfluidics Instrumentation (OMI) Lab of IISc, who developed it. ?Conventionally, sophisticated instruments like a chromatographer are used to detect melamine, which farmers and those outside of laboratories do not have access to. But using our device, one can detect the adulteration easily by the colour change that occurs when melamine is present in milk, which can be read by an optical reader built by us.?
The researchers have exploited the process by which melamine affects the formation of silver nanoparticles, in developing their optical reader. ?The optical device has reagents that react to form silver nanoparticles, which usually appears yellow. When melamine is present in milk, the formation of nanoparticles is disrupted and the reagents appear a different colour. Now, by analyzing the change in colour, the optical device can even tell us the concentration of melamine in units of parts per million (ppm),? explained Prateek Katare, another researcher at OMI Lab.
[caption id="attachment_3289" align="alignright" width="300"] Prototype to check quality of cocoon[/caption]
Silk is a natural fibre extracted from the cocoons of silk moths. The process of extraction requires selecting cocoons without defects which are then boiled to extract silk. Although India ranks second as the largest producer of silk, this critical process of assessing the quality of the cocoons is still done manually. Either the farmer who grows cocoons, or the reeler who purchases it, randomly selects a few cocoons from each batch, looks for visible defects using their eyes or by shaking the cocoon. This process leads to large number of defective cocoons still being mixed with the good ones, thus affecting the quality of the silk fibre.� To produce the best quality of silk, each cocoon needs to be tested, making it labour intensive and time consuming.
The instrument to check the quality of cocoons was developed by Prasobhkumar. It includes optics hardware system along with the software that could take each image containing about 96 cocoons and assess the quality of each of them in less than a second.
?We developed the image processing algorithm to detect the defects based on size, shape, colour and the position of the defect. Based on these four parameters and a set of 5 different templates of different types of good cocoons, the handheld system displays which type the defective cocoons are, besides what their number and percent are,? explained Prasobhkumar.
The researchers have also built an audio based detection system where the cocoon is vibrated� using a� robotic arm and a microphone attached to it, picks up the impact acoustic emissions made by the pupa as it hits the wall of the cocoon. Based on the sound, the software decides the quality of the cocoon.
?As a next step, we want to automate the whole process, by making a conveyor belt where the cocoons move, and a camera will take pictures. Next, the cocoons are made to roll down, while a microphone will listen to the sounds it produces. Based on the texture, shape, color and sounds, we can have a real-time quality assessment system for cocoons, which will boost the Indian silk market enormously? said Prof C R Francis, a Professor at the Department of Sericulture at Maharani?s Science College for Women, Bangalore.
OMI lab works on two fields of science - Optics and Microfluidics. ?In general, our lab develops a variety of instruments based on optics and microfluidics that have applications in healthcare, quality control, blood tests, water quality tests, adulterant detection and so on,? said Prof. Sai Siva Gorthi, an Assistant Professor at the Department of Instrumentation and Applied Physics at IISc, and the head of the OMI lab.
With inputs from Research Matters
Image courtesy: S. Varun and Prasobkumar
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