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Economically motivated adulteration (EMA) and/or cross-contamination are the two major factors resulting in the substandard quality of premium edible oil like extra virgin olive oil (EVOO) produced in food and beverage (F&B) fast-moving consumer goods (FMCG) industries. Current quality assurance methods (e.g., spectroscopy and chromatography) in FMCG involve intrusive sample extraction and ex situ analysis in a laboratory using expensive bulky instrumentation, which is neither integrable inline nor scalable to match the production throughput. Such techniques do not meet the industrial requirements of in situ testing, non-intrusive analysis, and high throughput inspection (100% product verification) leading to food loss and package waste from unwanted batch rejects. Herein, a low-cost electrical approach based on capacitance is proposed to show the proof of concept for screening EVOO-filled containers non-invasively for adulteration without any sample extraction by capturing the differences in the dielectric properties of mixed oils. The sensor system displayed a fast response (100 ms) and low detection limits for different adulterants (olive oil (32.8%), canola oil (19.4%), soy oil (10.3%) and castor oil (1.7%)), which is suitable for high-throughput (>60 sample/min) screening. Furthermore, a low-cost automated system prototype was realized to showcase the possibility of translating the proof of concept for possible scaling up and inline integration. [ABSTRACT FROM AUTHOR]

The concentration of glucose in biological fluids is in the micromolar range, the detection of which requires devices with high sensitivity and low limit of detection (LOD). Here, we report the real-time electronic detection of glucose using an antioxidant found in green tea, namely, epigallocatechin gallate (EGCG), decorated on carbon nanotubes (CNTs) and tested in a chemiresistor configuration. The detection principle relies on the spontaneous reaction of EGCG with hydrogen peroxide, a reactive oxygen species released during glucose oxidation, which is translated electrically as a change in CNT conductance. Our results suggest that the response of EGCG decorated CNTs was far superior to that of the bare CNT based device. The sensor detected glucose ranging from 10 nM to 1 μM with LOD of ∼8.7 nM, which is much lower than the commercially available finger-pricking based glucose sensors. This could pave the way for developing simple resistivity-based sensors capable of glucose detection in biological fluids other than blood, such as sweat and saliva. [ABSTRACT FROM AUTHOR]

In the aim towards fulfilling the versatile applications of carbon nanotubes (CNTs) in nanoelectronics, it is vital to control the alignment and orientation of ultralong and dense CNT arrays. Here, we have developed a subtle method to in situ improve the alignment of CNT arrays while maintaining their superior length and high density by introducing strong zipping and gas-guiding effects using trench structures on flat Si/SiO2 substrates. For CNTs suspended over the trenches, the zipping effect will induce strains into the nanotube body, and thus stretch the slack CNTs, resulting in the taut and straight morphology; for CNT segments sitting on substrate, the straightening is realized by promoting the gas-guiding effect through decelerating the “apparent” elongation rate of the growing CNTs. The improvement could always be observed no matter if the nanotube lies fully suspended across a trench, or is just partially suspended with its middle portion contacting the bottom of the trench. Based on the Raman characterization of individual CNTs and by taking the growth process into account, the improvement mechanism has been elaborately discussed. Our work demonstrates a simple and robust approach to grow aligned CNT architectures for electronic and mechanical applications. [ABSTRACT FROM AUTHOR]

We report on the dual mechanical and proximity sensing effect of soft-matter interdigitated (IDE) capacitor sensors, together with its modelling using finite element (FE) simulation to elucidate the sensing mechanism. The IDE capacitor is based on liquid-phase GaInSn alloy (Galinstan) embedded in a polydimethylsiloxane (PDMS) microfludics channel. The use of liquid-metal as a material for soft sensors allows theoretically infinite deformation without breaking electrical connections. The capacitance sensing is a result of E-field line disturbances from electrode deformation (mechanical effect), as well as floating electrodes in the form of human skin (proximity effect). Using the proximity effect, we show that spatial detection as large as 28 cm can be achieved. As a demonstration of a hybrid electronic system, we show that by integrating the IDE capacitors with a capacitance sensing chip, respiration rate due to a human's chest motion can be captured, showing potential in its implementation for wearable health-monitoring. [ABSTRACT FROM AUTHOR]

Skeletal muscle has the capacity to repair and heal itself after injury. However, this self-healing ability is diminished in the event of severe injuries and myopathies. In such conditions, stem cell-based regenerative treatments can play an important part in post-injury restoration. We herein report the development of a bioactive (integrin- β 1 antibody immobilized) gold micropatterned platform to promote human mesenchymal stem cell (hMSC) differentiation into myotube-like cells. hMSCs grown on bioactive micropattern differentiated into myotube-like cells within two weeks. Furthermore, the up-regulation of myogenic markers, multi-nucleated state with continuous actin cytoskeleton and the absence of proliferation marker confirmed the formation of myotube-like cells on bioactive micropattern. The prominent expression of elongated integrin- β 1 (ITG- β 1 ) focal adhesions and the development of anisotropic stress fibers in those differentiated cells elucidated their importance in stem cell myogenesis. Together, these findings delineate the synergistic role of engineered cell anisotropy and ITG- β 1 -mediated signaling in the development of myotube-like cells from hMSCs., (© 2021 IOP Publishing Ltd.)

Single-walled carbon nanotube (SWCNT)-based field-effect transistors (FETs) have been explored for use as biological/chemical sensors. Dopamine (DA) is a biomolecule with great clinical significance for disease diagnosis, however, SWCNT FETs lack responsivity and selectivity for its detection due to the presence of interfering compounds such as uric acid (UA). Surface modification of CNTs using single-stranded deoxyribonucleic acid (ssDNA) renders the surface responsive to DA and screens the interferent. Due to the presence of different bases in ssDNA, it is necessary to investigate the effect of sequence on the FET-based molecular recognition of DA. SWCNT FETs were decorated with homo- and repeated-base ssDNA sequences, and the electrical response induced by DA in the presence and absence of UA was gauged in terms of the variation in transistor electrical parameters including conductance, transconductance, threshold voltage and hysteresis gap. Our results showed that the response of ssDNA-decorated devices to DA, irrespective of the presence or absence of UA, was DNA sequence dependent and exhibited the trend: G > A > C and GA > GT > AC > CT, for homo- and repeated-base sequences, respectively. The different response of various SWCNT-ssDNA systems to DA underlines the sequence selectivity, whereas the detection of DA in the presence of UA highlights the molecular selectivity of the ssDNA-decorated devices.

A single-walled carbon nanotube (SWCNT) in a field-effect transistor (FET) configuration provides an ideal electronic path for label-free detection of nucleic acid hybridization. The simultaneous influence of more than one response mechanism in hybridization detection causes a variation in electrical parameters such as conductance, transconductance, threshold voltage and hysteresis gap. The channel length (L) dependence of each of these parameters necessitates the need to include them when interpreting the effect of L on the response to hybridization. Using the definitions of intrinsic effective mobility (µe) and device field-effect mobility (µf), two new parameters were defined to interpret the effect of L on the FET response to hybridization. Our results indicate that FETs with ≈300 µm long SWCNT exhibited the most appreciable response to hybridization, which complied with the variation trend in response to the newly defined parameters.