Milk Tester: Design, Development and Performance Study (2015 - 2020)

Problem/Need Addressed: Milk and its by-products are highly nutritious foods that are consumed, processed and marketed all around the world. However, they are at higher risk of being contaminated in different stages of processing. Milk analyzers should determine the quality of milk by analyzing its purity and quantifying the presence of nutritional components in it. Most of the commercial milk analyzers can measure the percentage of fat, SNF, protein, and lactose content of milk. Only three instruments are available to identify the adulteration in milk along with the fat, SNF, protein components; however, they are expensive (INR 4-5 lacs) and not suitable for the use of common people.

Opportunity: To make a low-cost and user-friendly milk tester, which will be easily affordable and no need of prior chemical or technical knowledge to operate it.

Proposed Solution: The innovation aims to develop a low-cost (component cost ~ INR 5000) 'Milk Tester' that can simultaneously determine the fat content and presence of adulterants in milk in an inexpensive way compared to the existing commercial milk analyzers.

Characterization of the sensor

Fig.1 (a) Photograph, (b) schematic, and (c) porous surface of the PMMA coated sensor.

The sensor is a rigid stick type polymethyl methacrylate (PMMA) coated copper cladded electrode. Milk has an inherent ionic property due to the presence of ions like calcium, sodium, potassium, chlorine in it. When the sensor is dipped into the milk sample, physical diffusion of ions takes place through the porous surface of the thin polymer film (Fig. 1(c)). The rate and nature of diffusion differ in different ionic concentration. Further, the ionic concentration of milk varies with the type and quantity of adulterant (contaminant) added to it. As the number of ions increases in the solution, its conductivity changes. This leads to the change in the effective impedance of the sensor. At a particular excitation frequency, pure and adulterated milk show different phase angle of the sensor impedance; which confirms the presence of adulterants in the milk sample

Soil Moisture Meter (2017 - 2019)

An appropriate proportion of water content in the soil is critical for plant growth. The use of capacitive soil moisture sensor exploits the very property of soil that the dielectric value of soil varies with the amount of water content. Use of capacitive sensors for soil moisture measurement provides some advantages such as better accuracy after soil-specific calibration, high sensitivity, flexibility in probe design, easy installation and cost-effectiveness. A copper cladded epoxy material, coated with thin film of polymethyl methacrylate (PMMA) is used here for soil moisture sensing.

Flexible and Printed Smart RFID Tag (2021 - 2022)

I joined the University of Glasgow in April 2021 as a postdoctoral researcher. This research work is being funded by the EU’s INTERREG VA Programme NWCAM. As a part of NWCAM, I am developing a smart tag with printed active/passive electronics devices such as RFIDs for health and food quality monitoring. Few of the sensing parameters such as temperature, humidity, volatile organic compounds (VOCs) like alcohol, and strain are identified which are crucial to detect the healing status of the wound or freshness in packaged meat and dairy products. The tag is based on a battery-less near-field communication (NFC) protocol where NFC enabled mobile phone with a custom app is used to provide the required power to the sensing tag and make real-time measurements of sensing parameters in user understandable way. In this tag, the interconnection between the silicon-based surface-mounted components is made by printed conductive silver ink on the top of the flexible substrate. This process combines the flexible substrate-based printing technology with the high-performing SMT (Surface Mounting Technology) components. In this direction, I have also explored the electrical bonding challenges of small (0.25 mm) pad SMT components in different substrates of the printed tag to have good mechanical stability and appropriate electrical contacts in the tag. This research is linked with our industry partner NuPrint Technologies and in near future, the tag will be commercially available as a label in healthcare and food quality monitoring applications.

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