LAUSR

Alkali metal ions such as lithium, sodium and potassium are essential chemical species present in biological fluids (0.5-1.2 mM) and less hazardous quantity (0.9 mu M-12 mu M) present in drinking water. Lithium salts are used in pharmaceuticals, in ores and minerals, in Li-ion batteries. Ingestion of water source containing lithium concentration above 0.2 mM affects normal functioning of the body. Hence it is important to detect these ions in potable water. Here, a conjugated molecule based sensor for detection of lithium ion in water is developed. The conjugated molecule has a receptor moiety to capture the ion. The conjugated molecule interaction with alkali metal ions - Li+,Na+ and K+ is studied by density functional theory and interference analysis. The resistive based sensor is fabricated and device characteristics are studied. The experimental and simulation results suggest that the conjugated molecule interaction specifically with Li+ is relatively stronger. The lower limit of detection of the sensor is observed to be 0.05 mM. This limit is within the range of the lithium ion concentration found in biological fluids.