Harish Makri Nimbegondi Kotresh

Galvanic Cell Type Sensor for Soil Moisture Analysis

Here we report the first potentiometric sensor for soil moisture analysis by bringing in the concept of Galvanic cells wherein the redox energies of Al and conducting polyaniline are exploited to design a battery type sensor. The sensor consists of only simple architectural components, and as such they are inexpensive and lightweight, making it suitable for on-site analysis. The sensing mechanism is proved to be identical to a battery type discharge reaction wherein polyaniline redox energy changes from the conducting to the nonconducting state with a resulting voltage shift in the presence of soil moisture. Unlike the state of the art soil moisture sensors, a signal derived from the proposed moisture sensor is probe size independent, as it is potentiometric in nature and, hence, can be fabricated in any shape or size and can provide a consistent output signal under the strong aberration conditions often encountered in soil moisture analysis. The sensor is regenerable by treating with 1 M HCl and can be used for multiple analysis with little read out hysteresis. Further, a portable sensor is fabricated which can provide warning signals to the end user when the moisture levels in the soil go below critically low levels, thereby functioning as a smart device. As the sensor is inexpensive, portable, and potentiometric, it opens up avenues for developing effective and energy efficient irrigation strategies, understanding the heat and water transfer at the atmosphere-land interface, understanding soil mechanics, forecasting the risk of natural calamities, and so on.

A vitamin C fuel cell with a non-bonded cathodic interface

Vitamin C is a naturally occurring molecule with antioxidant properties, and it often plays a pivotal role in many chemical and biochemical processes. We show that a cobalt-based molecular electrocatalyst can mediate the electron donation from vitamin C which upon coupling with a non-bonded and reversible electron acceptor; the electron flow between the half cells can be channeled in a precious-metal-free configuration. The non-bonded nature of the electron acceptor allows fast interfacial kinetics even on simple carbon particles and arrests the cathode-derived parasitic chemistry often encountered in oxygen breathing fuel cells. Consequently, a vitamin C fuel cell driven by the non-bonded cathodic interface demonstrates ∼18 times higher performance metrics compared to the precious-metal-based vitamin C–O2 configuration. Due to the renewable nature of the fuel and the precious metal-free configuration in the proposed non-bonded architecture, the cell can noticeably reduce the cost of electricity per kW with potential practical applications in powering commercial electrical appliances.

Synthesis, characterization and dielectric properties of sulfonated poly(1,3,4-oxadiazole-ether) sulfone copolymer with functional pendant carboxylic acid groups

This work reports the synthesis and electrical characterization of sulfonated copolymer with flexible carboxylic acid pendants with 1,3,4-oxadiazole unit in the main polymer structure contrived successfully via nucleophilic displacement polycondensation among 2,5-Bis(4-fluorophenyl)-1,3,4-oxadiazole (BFPOx), 4,4′-Bis(4-hydroxyphenyl) valeric acid (BPV) and Disodium-3,3′-disulfonate-4,4′-dichlorodiphenylsulfone (S-DCDPS). The molecular structural characterization of the copolymer was achieved by NMR spectroscopic studies, TGA was performed to verify the thermal stability, dielectric studies were executed by compressing the copolymer sample in to tablets and results were discussed.