The demand for self-powered, flexible, and wearable electronic devices has been increasing in recent years for physiological and biomedical applications in real-time detection due to their higher flexibility and stretchability. This work fabricated a highly sensitive, self-powered wearable microdevice with Poly-Vinylidene Fluoride-Tetra Fluoroethylene (PVDF-TrFE) nano-fibers using an electrospinning technique. The dielectric response of the polymer was improved by incorporating the reduced-graphene-oxide (rGO) multi-walled carbon nano-tubes (MWCNTs) through doping. The dielectric behavior and piezoelectric effect were improved through the stretching and orientation of polymeric chains. The outermost layer was attained by chemical vapor deposition (CVD) of conductive polymer poly (3,4-ethylenedioxythiophene) to enhance the electrical conductivity and sensitivity. The hetero-structured nano-composite comprises PVDF-TrFE doped with rGO-MWCNTs over poly (3,4-ethylenedioxythiophene) (PEDOT), forming continuous self-assembly. The piezoelectric pressure sensor is capable of detecting human physiological vital signs. The pressure sensor exhibits a high-pressure sensitivity of 19.09 kPa⁻¹, over a sensing range of 1.0 Pa to 25 kPa, and excellent cycling stability of 10,000 cycles. The study reveals that the piezoelectric pressure sensor has superior sensing performance and is capable of monitoring human vital signs, including heartbeat and wrist pulse, masticatory movement, voice recognition, and eye blinking signals. The research work demonstrates that the device could potentially eliminate metallic sensors and be used for early disease diagnosis in biomedical and personal healthcare applications.

Airborne microorganisms pose a significant health threat, causing various illnesses. Traditional detection methods are often slow and complex. This review highlights the potential of nanomaterial-based biosensors, particularly colorimetric sensors, for rapid and on-site detection of airborne microbes. Colorimetric sensors offer real-time visual detection without complex instrumentation. We explore the integration of these sensors with Lab-on-a-Chip technology using PDMS microfluidics. This review also proposes a novel PDMS-based colorimetric biosensor for real-time detection of airborne microbes. The sensor utilizes a color change phenomenon easily observable with the naked eye, simplifying analysis and potentially enabling point-of-care applications. Graphical Abstract

Antimicrobial viroblock/polyacrylonitrile nanofiber webs fabricated using the electrospinning method were assessed in terms of the antimicrobial activity against infectious agents as a potential material used in mask production. Viroblock (VB) is an amalgam of lipid vesicle and silver. Lipid vesicle depletes the virus outer membrane, which contains cholesterol, while silver ions penetrate the virus, interact with sulfur-bearing moieties, and possess the virus bactericidal property. VB, having anti-coronavirus and anti-influenza properties, was prepared in four different concentrations, 0.5 wt%, 1 wt%, 1.5 wt%, and 2 wt%, in regard to nanofiber weight. The resultant nanofibers were characterized by scanning electron microscope (SEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), water contact angle, water content, and thermogravimetric analysis (TGA). Moreover, all nanofibrous samples were evaluated for cell proliferation assay and ATCC antibacterial tests. Based on characterization results and cytotoxicity, the developed composite nanofibers-based webs showed good promise for utilization in anti-viral masks. Particularly, 2 wt% VB/PAN nanofibers have the highest antibacterial properties against negative and positive bacteria along with excellent cell viability.

The textile industry is one of the largest consumers of synthetic dyes and a principal contributor to industrial water pollution. This study examines the natural dyeing of silk fabric using aqueous extracts from the bark and leaves of Dalbergia sissoo (D. sissoo), widely available across South Asia, as a potential substitute for synthetic colourants. A four-factor Box–Behnken design was applied to optimize the dyeing conditions for each plant part. Dye concentration, mordant type (alum, tannic acid and gallnut), mordant method (pre, meta and post) and mordant concentration were the variables for the bark dataset, while sodium chloride concentration replaced the mordant method for the leaves dataset. The dyed samples were characterized in terms of colour strength (K/S), CIELAB colour coordinates and the principal fastness properties, and the K/S response was visualized through three-dimensional response surface and contour plots. The bark extract produced shades from pale yellow to deep reddish-brown with K/S values between 0.34 and 3.59, the deepest obtained with gallnut pre-mordanting at 30% dye and 30% mordant concentration. The leaves extract produced brighter yellow to yellow–green shades with K/S values between 0.62 and 1.44, the deepest obtained with alum at 15% mordant concentration combined with 20 g/L sodium chloride. Rubbing fastness and multifiber staining of both substrates fell between grades 4 and 5, and the colour-change rating between 1/2 and 2/3. The results establish D. sissoo as a viable dual-source natural colourant delivering two distinct colour palettes from a single tree species.