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Conducting and Conjugated Polymers for Biosensing Applications
Published in John R. Reynolds, Barry C. Thompson, Terje A. Skotheim, Conjugated Polymers, 2019
C. Pitsalidis, A.M. Pappa, C.M. Moysidou, D. Iandolo, R.M. Owens
The use of phospholipids was described by Magliulo and colleagues who developed a BIOEGOFET.156 In their study, a layer of streptavidin-functionalized phospholipids was deposited on the gate surface of an electrolyte-gated organic field-effect transistor (EGOFET) with a P3HT channel. This device presented an LOD of 10 nM with a dynamic range of 10 nM–1 μM. The advantages of the developed system, in comparison to other available solutions, lay in the wide dynamic range as well as the possibility of working in a high ionic strength electrolyte solution. The mode of action can be explained taking into account the binding of negative species/anions to the surface of a dielectric layer (the phospholipid bilayer) at the interface with a p-type material (i.e., P3HT) when a negative bias is applied at the gate. This, in turn, results in the accumulation of positive charges on the surface of the conducting polymer. The binding of the negatively charged streptavidin molecules to biotin on the phospholipid layer induces more holes in the transistor channel, registered as an increase in the measured current. Control experiments were run in order to assess the specificity of the binding event and its mechanism.
HgCdTe Detectors
Published in Antoni Rogalski, Infrared and Terahertz Detectors, 2019
The ion implantation in HgCdTe is a well-established approach for fabricating HgCdTe photovoltaic devices with n-on-p type junctions [284,285]. It is a common method of HgCdTe photodiode fabrication since it avoids heating of this metallurgically sensitive material and permits a precise control of the junction depth. Many manufacturers obtain the desired p-type level by controlling the density of acceptor-like Hg vacancies within a carrier concentration range of 1016–1017 cm−3. The n+-p structures are produced by Al, Be, In, and B ions implantation into vacancy-doped p-type material, but the technique typically uses ion implantation of light species (usually B and Be) to form n-region. B is possibly most frequently used, perhaps due to the fact that B is also a standard implant for Si. Regardless of the nature of the implanted species, an n-type electrical activity is associated with implantation damage as observed first by Foyt et al. [286].
Synthesis and Characterization of Al-Doped SnO2 Thin Films
Published in Nandakumar Kalarikkal, Sabu Thomas, Obey Koshy, Nanomaterials, 2018
Figure 1.8 shows the effect of Al-doping concentration on the response of sensor operated at 275°C. It is observed that the sensor response increases with Al-doping concentration up to 1 wt% and decreases afterwards. The effect of doping can be explained as follows. Al-doping can have several effects on the properties important to gas-sensing applications, including inhibiting SnO2 grain growth, modifying the electron Debye length and modifying the gas-surface interactions.1 Another important role of Al-doping is that the substitution of Sn4+ by Al3+ acts as an acceptor impurity, forming localized p-regions in n-type SnO2, forming the p-n junctions.25–27 This may increase the depletion barrier height due to the electron transfer from n-type to p-type materials. When the sensor is exposed to CO gas, the electrons trapped by adsorbed oxygen species and p-type materials are fed back to the n-type material through surface interactions, resulting in a decrease in sensor resistance, improving the sensor response significantly (Fig. 1.8).1
Ultrasonic Nondestructive Evaluation of Additively Manufactured Photopolymers
Published in Research in Nondestructive Evaluation, 2022
Luz D. Sotelo, Amelia O. Vignola, Celeste A. Brown, Kaushik Sampath, Matthew D. Guild
The materials evaluated in this study comprised 14 different photopolymers: VeroClear, VeroBlack, VeroBlue, VeroGrey; an acrylonitrile butadiene styrene-type material, ABSPlus; a thermoplastic elastomer-type material called TangoPlus; and a set of materials that mix both VeroClear and TangoPlus in varying ratios for customized stiffness, hardness, and toughness [31].