A scalable
method for the assembly of oriented bacterial cellulose
(BC) films is presented based on using wrinkled thin silicone substrates
of meter-square size as templates during biotechnological syntheses
of BC. Control samples, including flat templated and template-free
bacterial cellulose, along with the oriented BC, are morphologically
characterized using scanning electron microscopy (SEM). Multiple functional
properties including wettability, birefringence, mechanical strength,
crystallinity, water retention, thermal stability, etc., are being characterized for the BC samples, where the wrinkling-induced
in situ BC alignment not only significantly improved material mechanical
properties (both strength and toughness) but also endowed unique material
surface characteristics such as wettability, crystallinity, and thermal
stability. Owing to the enhanced properties observed, potential applications
of wrinkle templated BC in printing and cell culture are being demonstrated
as a proof of concept, which renders their approach promising for
various biomedical and packaging applications.
Metal‐semiconductor nanostructures in various configurations are extensively used in photodetection, photocatalysis, and photovoltaics. For photodetection purposes, the working principle is straightforward; on illumination, generated charge carriers in excess lead to a decrease in resistance. Notably, using an interconnected metal‐semiconductor grating, it is observed and now reported an opposite response, an increase in the resistance. Such photoresistors are fabricated through wrinkle structuring and oblique angle material deposition methods. It is found that the controlled wrinkling leads to large‐area 1D periodic structures with coexisting cracking perpendicular to the grating direction—such cracks are used as connections between the two‐point contact measurement through the associated gold layer deposition. An enhanced current reduction is further observed on photoexcitation for an additional deposition of an amorphous titania layer. Subsequently, a discussion on the mechanisms and interaction between hot electron injection, charge carrier recombination, and thermalization is presented. Supported by numerical modeling, the angle‐resolved plasmonic modes with the photoresistance can be correlated. The ease of layered deposition of the materials allows one to extend the studies on cavity‐based structures with sandwiched titania layers as hotspots. This simple, scalable, and robust fabrication method thus promises an efficient routeway toward photosensor development in which plasmon‐mediated hot electrons play a crucial role.
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