Chemiresistive Polymer Percolation Network Gas Sensor Created with a Nanosphere Template

Abstract

different gas sensing devices including chemiresistors, [8] transistors, [9] and optical sensors. [10] Furthermore, molecular semiconductor-doped insulator heterojunctions based on small molecules have been designed to achieve stable gas detection. [11] Among various materials and device configurations, CP-based chemiresistors are regarded as one of the simplest methods of gas sensing. [12] CPs are deposited as a sensing layer during device fabrication, and interactions between the CPs and the analyte gas molecules cause changes in the electrical conductivity of the sensing layer that can be easily monitored.Sensitivity is one of the most significant parameters for the sensing performance of chemiresistors and various approaches have to date been developed to improve it. Among all the reported approaches, nanostructuring is regarded as an effective strategy because morphologies with higher surface areato-volume ratios can increase the sensitivity by improving the diffusion rate of gas molecules into and out of the CP-based sensing layers as well as providing more binding sites. To create nanostructured surfaces, CPs have in the past been fabricated through complex processes into different structures, including nanotubes, nanowires, nanoribbons, nanoparticles, and nanofibers. [13] Electrical percolation is another effective approach to improve sensitivity. [14] For CP-based chemiresistors, electrical percolation is identified by the sharp increase in conductance between two electrodes during polymer deposition. In the percolation region, a relatively small number of electrical bridges are formed between the electrodes compared with a thin film. CP-based chemiresistors based on percolation networks are more sensitive compared to their thin-film counterparts. This is because the conductivity of an entire percolation pathway will be disrupted by the interaction of the analyte anywhere along the pathway, and this means that a small number of interactions between the analyte molecules and the CP percolation network will lead to a relatively large resistance change. On the other hand, for CP thin film sensors, the analyte only locally affects the surface conductivity of the thin film, resulting in lower sensitivity. Previous work has shown that electropolymerization can be used to fabricate chemiresistors based on polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) percolation networks. [15] The sensitivities and limits of detection of the The sensitivity and limits of detection (LOD) of chemiresistive gas sensors can often be improved by increasing the surface area of the sensing material that interacts with the analyte. This process is referred to as nano structuring. Nanostructured polypyrrole (PPy) chemiresistive sensors for ammonia detection were created with the aid of a nanosphere template. Poly styrene nanospheres are deposited to form a template between interdigitated electrodes, and chronoamperometry is then used to grow PPy between the electrodes within the gaps of the nanospheres. The PPy grow...

Electrochemical Biosensor for Protein Concentration Monitoring Using Natural Wood Evaporation for Power Generation

“…Therefore, the chronoamperometry method, which detects current changes in real time, − and alternating current (AC) impedance method, which is used to measure the impedance of the sensor itself, − were chosen as feasible and more sensitive detection methods. In addition, the sensor itself needs to have some affinity for the protein being detected. , Many high-cost modified synthesized materials, such as silicon materials, , magnetic nanocomposites, , metal–organic frameworks, and porous polymer materials have been reported to be effective in achieving the affinity effect on proteins.…”