Publications

Flexible and biocompatible strain sensors are becoming increasingly important in fields such as health monitoring, wearable electronics, and environmental sensing because they offer significant advantages over conventional rigid systems. However, they lack the versatility and ecological and physiological biocompatibility necessary for broader integration within biological systems. Here, we describe the development of an inexpensive water-based plasticized chitosan-carbon black composite ink that can be used to produce conductive and biocompatible strain sensors. The ink can be applied to various surfaces, including skin, internal organs, and other biological tissues, using numerous methods, such as painting, dipping, and stamping. Furthermore, this unprecedented ability to attach and conform to biological surfaces allows the exploration of secondary sensing innovations, such as exploiting skin wrinkles to improve sensitivity. This study demonstrates that the ink exhibits a reliable change in electrical resistance in response to a wide range of motions, from subtle vibrations during speech and heartbeats to extensive articulations, like finger and elbow movements. This exceptional sensitivity range, biocompatibility, and the ink's low cost, biodegradability, and ease of removal enhance its applicability in sustainable, temporary, and customizable sensing solutions, highlighting its potential for versatile applications in human health monitoring, motion detection, and environmental sensing.

JTD Keywords: Blac, Chitin, Composites, Performance strain sensors

In this study, we compare for the first time the nanomechanical properties of lipid bilayer islands on flat and porous surfaces. 1,2-Dimyzistoyl-sn-glycero-3-phosphatidylcholine (DMPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) bilayers were deposited on flat (silicon and mica) and porous silicon (pSi) substrate surfaces and examined using atomic force spectroscopy and force volume imaging. Force spectroscopy measurements revealed the effects of the underlying substrate and of the lipid phase on the nanomechanical properties of bilayers islands. For mica and silicon, significant differences in breakthrough force between the center and the edges of bilayer islands were observed for both phospolipids. These differences were more pronounced for DMPC than for DPPC, presumably due to melting effects at the edges of DMPC bilayers. In contrast, bilayer islands deposited on pSi yielded similar breakthrough forces in the central region and along the perimeter of the islands, and those values in turn were similar to those measured along the perimeter of bilayer islands deposited on the flat substrates. The study also demonstrates that pSi is suitable solid support for the formation of pore-spanning phospholipid bilayers with potential applications in transmembrane protein studies, drug delivery, and biosensing.

JTD Keywords: Black lipid-membranes, Gold surfaces, Supported bilayers, Channel activity, Micro-BLMS, Silicon, Proteins, Vesicles, AFM, Temperature measurement