Bioelectronics enables the study of the aqueous media that host soft tissues and interfaces for their proper function, as well as of the connections between various cells and/or organs, which communicate by exchanging specific ions and biomolecules 1 . The fundamental properties of the biological systems set the requirements of the electronics counterpart. Electrolyte-gated transistors (EGTs) have emerged as important building blocks for enhanced bioelectronics because they are stable in an aqueous environment, operate at low voltages and can transduce and amplify biological signals into electronic signals [2][3][4][5] .EGTs are three-terminal devices where the conductivity of a semiconducting material connected to two electrodes, classified as the source and the drain, is modulated by a third electrode known as the gate. In a basic EGT, the gate electrode and the semiconducting channel are in direct contact with the electrolyte. A voltage V G and V D is applied at the gate and drain electrode, respectively (Fig. 1a). V G and V D are referenced to the source voltage, which is typically set to ground, V S = 0 V. The polarity and magnitude of the voltage applied to the gate electrode result in a drift of cations or anions from the electrolyte to the semiconducting channel. The ionic charges can enhance or deplete the electronic charges residing in the semiconductor channel. This ionicelectronic modulation gives rise to a large variation of the channel conductivity that, in turn, manifests in a large modulation of the electronic source to drain current flowing through the transistor channel. Upon application of the gate, source and drain voltages, ions drift into the electrolyte and accumulate at the gate and semiconductor. The sign of the gate voltage controls the charge type of these ions (cations or anions), whereas its magnitude controls their density. For example, when a positive gate voltage is applied, the anion concentration increases at the gate and the cation concentration increases at the semiconducting channel. The sub-nanometre scale dimension of the ions interacting with the gate and channel materials results in a large electrostatic interaction at the gate/electrolyte and electrolyte/channel interfaces, which yields the low-voltage operation of EGTs that can range from a few volts to even less than 1 V, depending on the specific materials used. The low-voltage operation is critically important for electrophysiology and in the case of a large variety of biosensors. In addition, in contrast to the conventional thin-film field-effect transistors, in EGTs the gate is not required to be positioned in front of the channel as the charge modulation is due to the accumulation or depletion of ions transported within
The aims of this study were to evaluate the incidence of white striping (WS) under commercial conditions and assess its effect on some quality traits in broiler breast fillets. In the first experiment, occurrence of WS (absence = normal; presence classified in 2 levels as moderate or severe) was assessed in a major commercial processing plant on 28,000 breast fillets (pectoralis major muscles) chosen at random from 56 flocks of broilers processed at 45 to 54 d of age. In the second experiment, 153 fillets were selected based on WS degree (normal, moderate, or severe) and used to assess ultimate pH, color, drip loss, cook loss, and Allo-Kramer-shear force on raw meat as well to determine marinade uptake, purge loss, cook loss, total yield, and Allo-Kramer-shear force after tumbling with a 15% (wt/wt) solution containing sodium tripolyphosphate (2.3%) and sodium chloride (7.6%). The total incidence of white striped breast fillets was 12.0% (8.9 and 3.1% in moderate and severe degree, respectively). Considering the effect of genotype, high-breast yield hybrids exhibited a higher overall incidence of WS compared with standard breast yield birds (15.2 vs. 10.0%; P ≤ 0.001). Severe fillets showed higher pH than moderate and normal groups (5.95 vs. 5.88 and 5.86; P ≤ 0.05). Fillets with severe and moderate WS also exhibited lower marinade uptake compared with normal fillets (7.92 vs. 10.97 vs. 12.67%; P ≤ 0.05). Moreover, cook losses increased as the degree of WS increased from normal to severe groups in both raw (21.27 vs. 23.20 vs. 26.74%; P ≤ 0.05) and marinated meat (14.59 and 14.84 vs. 15.93%; P ≤ 0.05). Finally, nonmarinated fillets with severe striping had lower Allo-Kramer-shear force compared with moderate and normal ones (3.69 vs. 4.41 and 4.91 kg/g; P ≤ 0.05). In conclusion, this study revealed the importance achieved by WS defects in the production of broiler meat as well as its very negative impact on water holding and binding capacity of breast meat.
The application of organic electronic materials for the detection of ionizing radiations is very appealing thanks to their mechanical flexibility, low-cost and simple processing in comparison to their inorganic counterpart. In this work we investigate the direct X-ray photoconversion process in organic thin film photoconductors. The devices are realized by drop casting solution-processed bis-(triisopropylsilylethynyl)pentacene (TIPS-pentacene) onto flexible plastic substrates patterned with metal electrodes; they exhibit a strong sensitivity to X-rays despite the low X-ray photon absorption typical of low-Z organic materials. We propose a model, based on the accumulation of photogenerated charges and photoconductive gain, able to describe the magnitude as well as the dynamics of the X-ray-induced photocurrent. This finding allows us to fabricate and test a flexible 2 × 2 pixelated X-ray detector operating at 0.2 V, with gain and sensitivity up to 4.7 × 104 and 77,000 nC mGy−1 cm−3, respectively.
The development of wearable chemical sensors is receiving a great deal of attention in view of non-invasive and continuous monitoring of physiological parameters in healthcare applications. This paper describes the development of a fully textile, wearable chemical sensor based on an organic electrochemical transistor (OECT) entirely made of conductive polymer (PEDOT:PSS). The active polymer patterns are deposited into the fabric by screen printing processes, thus allowing the device to actually “disappear” into it. We demonstrate the reliability of the proposed textile OECTs as a platform for developing chemical sensors capable to detect in real-time various redox active molecules (adrenaline, dopamine and ascorbic acid), by assessing their performance in two different experimental contexts: i) ideal operation conditions (i.e. totally dipped in an electrolyte solution); ii) real-life operation conditions (i.e. by sequentially adding few drops of electrolyte solution onto only one side of the textile sensor). The OECTs response has also been measured in artificial sweat, assessing how these sensors can be reliably used for the detection of biomarkers in body fluids. Finally, the very low operating potentials (<1 V) and absorbed power (~10−4 W) make the here described textile OECTs very appealing for portable and wearable applications.
PSS represent an important milestone in wearable monitoring, as they present an easy and reproducible fabrication process, very good performance in wet and dry (at rest) conditions and a superior level of comfort with respect to textile electrodes proposed so far. This paves the way to their integration into smart garments.
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