Venkateswaran Vivekananthan

Highly Directional 1D Supramolecular Assembly of New Diketopyrrolopyrrole-Based Gel for Organic Solar Cell Applications.

A new thermoreversible organogel based on diketopyrrolopyrrole dye (DPP-NCO) is reported for the first time and evolved as a new building block for the fabrication of 1D supramolecular assembly. AFM analysis illustrated that its gel state is composed of different sized 1D rods. DPP-NCO gel used as an additive in organic solar cells yields high efficiency of 7.9% owing to better nanophase separation of its active layer.

A sustainable freestanding biomechanical energy harvesting smart backpack as a portable-wearable power source

Wearable gadgets have attracted consumer attention, resulting in an abundance of research on the development of self-powered devices. Recently, triboelectric nanogenerators (TENGs) have been shown to be an effective approach for scavenging biomechanical energy. An innovative, cost-effective and eco-friendly freestanding smart backpack-triboelectric nanogenerator (SBP-TENG) is presented for scavenging biomechanical energy. A new approach to creating irregular surfaces on a polydimethylsiloxane (PDMS) film is demonstrated by recycling a plastic Petri dish discarded after laboratory usage. The SBP-TENG relies on contact and separation electrification between the PDMS film and contact materials (wool, paper, cotton, denim and polyethylene). The performance of single- and multi-unit SBP-TENGs is systematically studied and real-time energy harvesting from human motions, such as walking, running and bending, is demonstrated. This study confirms that the SBP-TENG is an excellent technology for scavenging biomechanical energy, capable of driving a variety of low-power electronic devices such as global positioning system (GPS) sensors, wearable sensors and flashlights.

Biocompatible collagen-nanofibrils: An approach for sustainable energy harvesting and battery-free humidity sensor applications

In contrast with the conventional ceramic/oxide humidity sensors (HSs), a self-powered piezoelectric biopolymer HS with reasonable sensitivity, reliability, and a nontoxic and eco-friendly nature is highly desirable. A piezoelectric nanogenerator (PNG)-driven biopolymer-based HS provides a pathway toward a sustainable and greener environment in the field of smart sensors. For that, a piezoelectric collagen nanofibril biopolymer coated on to a cotton fabric has dual functionality (energy harvesting and sensor). Collagen PNG generates a maximum of 45 V/250 nA upon 5 N and can also work as a sensor to measure various percentages of relative humidity (% RH). The HS shows a linear response with a good sensitivity (0.1287 μA/% RH) in the range of 50-90% RH. These results open a field of eco-friendly multifunctional nanomaterials toward the development of noninvasive, implantable smart bio-medical systems.