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The objective of this study is to develop a portable hand held diagnostics platform for monitoring pollutants and water quality testing. We are developing a lab-on-chip (LOC) device for in-situ synthesis of gold nano-particles and for using a colorimetric peptide assay for water quality monitoring. The gold nano-particles are synthesized in-situ in our experiments. The gold nano-particles exhibit various optical properties due to their Surface Plasmon Resonance (SPR). These stabilized mono-disperse gold nano-particles are coated with bio-molecular recognition motifs on their surfaces. The stabilization and functionalization with bio-molecular recognition motif provides flexibility for various applications. For example, the gold nano-particles synthesized by this process are tested for their ability to be recognized by a surface coated with anti-Flg antibodies. The LOC consists of micro-wells housing different reagents and samples that feed to a common reaction chamber. The reaction products are delivered to several waste chambers in a pre-defined sequence to enable subsequent reagents/ samples to flow into the reaction chamber. Passive flow actuation is obtained by capillary driven flow (wicking). Dissolvable micro-structures are used as passive micro-valves that actuate at predefined intervals and do not require any external power source for actuation. The microfluidic chip (LOC) and the dissolvable microstructures are fabricated using soft lithography techniques. The passive valves are incorporated into the microfluidics platform by novel micro-fabrication and bonding techniques.

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Photolithography, typically used to create microchannel networks on silicon to fabricate the template for microfluid devices, has the drawback of requiring sophisticated instruments, available only in few premier fabrication units. Template fabrication thus was a privilege of few researchers. Through the years, researchers economised the process of device development using a three-dimensional (3D) printer which directly projected non-planar structures on to a photo-curable resin. Devices thus built lacked the versatility of polydimethylsiloxane (PDMS). The novelty of this work is to use the 3D printing resin for template fabrication and subsequent device development with PDMS. In this way, cost reduction and ease of template generation are substantially enhanced while retaining the advantages of a PDMS device. Unlike directly printed devices that are formed from ultraviolet curable photopolymer, this method fabricates the master with cured photopolymer used in 3D printing. The master pattern is transferred to PDMS for subsequent processing to construct the device. Compared to devices built on silicon templates, PDMS on polymer templates necessitate careful curing at a lower temperature. Low-temperature PDMS-substrate bonding has also been studied in this work. Fabricated device has channel dimensions in the order of 200-300 μm and has been used to study various oil-water emulsions.

Rhizoctonia solani Kuhn, is one of the most important pathogen of rice causing the sheath blight disease which accounts for heavy crop losses in all the major rice growing areas of the world, including tropical Asia. The proliferation of this soil borne pathogen depends on many abiotic factors. The two most common factors associated with the growth and spread of the pathogen is pH and temperature which has been studied in the present study. Both pH and temperature had significant effect on the growth of the fungal mycelial and sclerotial formation. A non-linear regression model for growth of the fungal mycelia revealed that growth occurred best at pH 6.0 and temperature 30°C for all treatments studied. No growth was observed below 15°C. In agricultural fields sclerotia, forms the means for the spread of the pathogen causing secondary disease incidence as well as survival of the pathogen in harsher conditions. Sclerotia formed between the temperatures of 20°C and 30°C, with an optimum at 30°C and pH 6.0. DOI: http://dx.doi.org/10.3126/ijls.v8i2.10226    International Journal of Life Sciences Vol.8(2): 2014; 4-9