Daukiya, Lakshya

An electronic counter is an integral component in an analog to digital (A/D) or digital to analog signal conversion circuit. The number of flip-flops (n) in these devices decides the quality of the conversion as the output is proportional to 2n. Since each flip-flop is a combination of transistors, and each transistor occupies some space, there is a limitation in the quality of conversion. The smallest 4-bit asynchronous counter is built by using a self-assembled redox-active organic molecule 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), where each DDQ molecule is acting as an individual flip-flop which is the building block of a counter. These molecules reduce the size of the counter by two orders. The output of the counter is obtained by tracking the translational motion of a group of molecules which are oscillating about the average value concerning the applied bias. Sixteen new spatial locations are obtained corresponding to sixteen distinct analog inputs (bias voltage) to the flip-flops. So, unconventional conversion of an analog signal to ultra-digital (UD) signal is possible by using an n-bit counter consisting of as many numbers of flip-flops and thus can become a system for the conversion of A/UD signal.

Graphene has been widely explored as an ideal platform for gas sensing owing to exceptional properties, such as its atom-thin two-dimensional conjugated structure and large specific surface area. Herein, we report that, by introducing covalent C-F bonds via site-selective ion-beam-induced fluorination, graphene sensing response to ammonia gas can be considerably improved due to the enhanced gas adsorption on the surface of fluorinated graphene. The response to the ammonia gas increased by a factor of eight together with the limit of detection approaching 65 ppb. The absorption kinetics between the ammonia gas and fluorinated graphene were analyzed by using the Langmuir isotherm model and the result shows that the enhanced sensitivity is mainly attributed to the strong binding energy of fluorinated graphene to ammonia gas molecules, which is consistent with previous theoretical predictions.