Venkatarao Selamneni

This work presents the design and simulation of DEP electrodes with an interdigitated electrode (IDE) pattern for the alignment of 1D nanostructures using COMSOL simulations. The impact of electric field distribution with varying electrode geometry, voltage, and frequency were studied using these simulations. The maximum electric field value of 2.6 × 10⁶ V/m was observed at electrode edges and gaps. Moreover, a significant increase in the electric field was observed with a decrease in finger width. These simulation results for DEP electrodes have huge potential in advancing 1D nanowire-based flexible and wearable electronic devices in the future.

Atomically thin two-dimensional (2D) materials have gained significant attention from the research community in the fabrication of high-performance optoelectronic devices. Even though there are various techniques to improve the responsivity of the photodetector, the key factor limiting the performance of the photodetectors is constrained photodetection spectral range in the electromagnetic spectrum. In this work, a mixed-dimensional 0D/2D SnS₂-QDs/monolayer MoS₂ hybrid is fabricated for high-performance and broadband (UV–visible–near-infrared (NIR)) photodetector. Monolayer MoS₂ is deposited on SiO₂/Si using chemical vapor deposition (CVD), and SnS₂-QDs are prepared using a low-cost solution-processing method. The high performance of the fabricated 0D/2D photodetector is ascribed to the band bending and built-in potential created at the junction of SnS₂-QDs and MoS₂, which enhances the injection and separation efficiency of the photoexcited charge carriers. The mixed-dimensional structure also suppresses the dark current of the photodetector. The decorated SnS₂-QDs on monolayer MoS₂ not only improve the performance of the device but also extends the spectral range to the UV region. Photoresponsivity of the device for UV, visible, and NIR region is found to be ∼278, ∼ 435, and ∼189 A/W, respectively. Fabricated devices showed maximum responsivity under the visible region attributed to the high absorbance of monolayer MoS₂. The response time of the fabricated device is measured as ∼100 ms. These results reveal that the development of a mixed-dimensional (0D/2D) SnS₂-QDs/MoS₂-based high-performance and broadband photodetector is technologically promising for next-generation optoelectronic applications.

This report demonstrates the fabrication and performance of a novel, transient, stable breath sensor based on black phosphorus quantum dots (BPQDs) and polyvinyl alcohol (PVA) composite. BPQDs were utilized as the conduction medium, while the PVA provides a flexible substrate that disintegrates in water. The device presents an innovative solution to black phosphorous (BP) degradation in which the copper (Cu) contacts are placed within the filler of the composite, ruling out the effects of surface degradation in the evaluation of the device performance. Stability studies at the end of eight weeks have been included wherein a negligible change in device performance to breath is observed. The sensor demonstrates chemiresistive properties with a change in resistance of ~100% to exhaled breath. The fabricated device was successful in identifying different breath patterns by monitoring the amplitude and the frequency of the device's current change upon exposure to breath. The fabricated device achieves complete transience in ~10 min when immersed in water. The study opens up possibilities for applications in the fields of biosensors, military, and consumer electronics.

The effective incorporation of novel and highly conductive hybrid functional nanomaterials onto flexible and porous substrates is extremely desirable to develop flexible supercapacitors. Herein, a novel 2D/0D-MoS₂/SnS₂ on a flexible cellulose paper substrate has been demonstrated for its utilization in flexible supercapacitors. The surface morphology and particle size of the MoS₂ and SnS₂ QDs, elemental composition, absorption spectra, and crystallinity have been analyzed thoroughly. Further, to explore the supercapacitor applications, the electrochemical response has been studied. The obtained results demonstrate that both the pristine MoS₂ and MoS₂/SnS₂ QDs composites on cellulose paper exhibited excellent electrochemical performance. The specific capacitance for the pristine MoS₂ and MoS₂/SnS₂ QDs displayed 422.2 F g⁻¹ and 277.1 F g⁻¹ at 0.5 A g⁻¹ current density using a conventional two-electrode system. The drop-casting of SnS₂ QDs provides better electrochemical active sites, which contributed to the enhanced specific capacitance of the composite structure. Moreover, it is shown that cellulose paper as an electrode material, using MoS₂ and MoS₂/SnS₂ QDs, is applied as a supercapacitor for potential utilization in wearable electronics applications.

This work demonstrates large-area growth of SnS₂ on a Gr dip-coated paper substrate and its application as an efficient broadband photodetector.

Even though there are reports on flexible photodetectors, one of the main issues that still needs to be resolved is the lower values of responsivity arising due to the use of non‐conventional substrates such as polymers, cellulose paper, etc. There are ways to improve the responsivity, such as piezotronics and surface plasmonic resonance, but studies on utilizing the same for flexible substrates remain limited. Further, the comparative performance of different nanoparticles (NPs) remains unexplored. This report demonstrates the fabrication of flexible visible/near‐infrared (NIR) photodetectors by functionalizing MoS₂ grown on paper substrate with various noble metal NPs such as gold (Au), platinum (Pt), and palladium (Pd) for enhanced photoresponse. The metal NPs‐MoS₂ (Au, Pt, and Pd‐NPs‐MoS₂) based photodetector shows a prominent improvement in the photoresponse characteristics when compared to pristine MoS₂. Enhancement in the photodetector performance is mainly due to the localized surface plasmon resonance of prepared metal NPs and the increase in incident light scattering. Out of the fabricated metal NPs‐MoS₂ photodetectors, Au‐NPs/MoS₂ shows maximum responsivity of 99.3 and 46.03 mA W⁻¹ under visible and NIR region, respectively which is ≈80 times higher than pristine MoS₂.

Over the last decade, the rapid development in health care industry and security have driven innovations in the field of wearable electronics and smart sensors. This report demonstrates the fabrication of Molybdenum diselenide (MoSe2) by a facile, low-cost and scalable hydrothermal synthesis method followed by a vacuum filter deposition on cellulose paper. The fabricated device is utilized as a pressure and strain sensor. Fabricated device is passivated using polydimethylsiloxane (PDMS) and also PDMS film enhances flexibility of the device. The calculated sensitivity of pressure sensor is ~ 0.3 kPa-1, which is comparable and relatively better than the pressure sensor fabricated using sophisticated techniques. Further, the device exhibited significant of merit for strain sensing with a gauge factor of ~ 6.84. Fabricated device showed excellent resilience in 500 cycle bending tests which promises the robustness of the device. As an application, the fabricated sensor is used to develop a wireless keyboard by integrating the sensor on fingertips of an individual and a real-time human motion monitoring application wherein the data is transmitted wirelessly to a smartphone with a dedicated android application. The successful fabrication of MoSe2/paper based cost-effective, flexible, and biodegradable pressure-strain sensor shows tremendous applications in future intelligent user interface systems, human security and personal health care monitoring.

With the advent of the recent coronavirus pandemic, it has become crucial to maintain social distancing within public spaces. To achieve this, it is important to keep a count of the number of people entering the premises and maintain low occupancy within it. This paper presents a very large area pressure sensor based on nickel sulfide (NiS) deposited on a paper using facile hydrothermal, and sheet to sheet vacuum filtration technique followed by an encapsulation of the sensor using polydimethylsiloxane (PDMS) for smart floor applications. An android application is also developed for the count of the people and the estimated waiting period for the entry.