A multi-functional ammonia gas and strain sensor with 3D-printed thermoplastic polyurethane-polypyrrole composites

Programmable and Modularized Gas Sensor Integrated by 3D Printing

The rapid advancement of intelligent manufacturing technology has enabled electronic equipment to achieve synergistic design and programmable optimization through computer-aided engineering. Three-dimensional (3D) printing, with the unique characteristics of near-net-shape forming and mold-free fabrication, serves as an effective medium for the materialization of digital designs into usable devices. This methodology is particularly applicable to gas sensors, where performance can be collaboratively optimized by the tailored design of each internal module including composition, microstructure, and architecture. Meanwhile, diverse 3D printing technologies can realize modularized fabrication according to the application requirements. The integration of artificial intelligence software systems further facilitates the output of precise and dependable signals. Simultaneously, the self-learning capabilities of the system also promote programmable optimization for the hardware, fostering continuous improvement of gas sensors for dynamic environments. This review investigates the latest studies on 3D-printed gas sensor devices and relevant components, elucidating the technical features and advantages of different 3D printing processes. A general testing framework for the performance evaluation of customized gas sensors is proposed. Additionally, it highlights the superiority and challenges of programmable and modularized gas sensors, providing a comprehensive reference for material adjustments, structure design, and process modifications for advanced gas sensor devices.

Fabrication of polypyrrole gas sensor for detection of NH3 using an oxidizing agent and pyrrole combinations: Studies and characterizations

The organic polymer known as Polypyrrole (Ppy) is synthesized when pyrrole monomers are polymerized. Excellent thermal stability, superior electrical conductivity, and environmental stability are all characteristics of Polypyrrole. Chemical oxidative polymerization was used to synthesize Ppy using Ferric chloride (FeCl₃) as an oxidizing agent and surfactant CTAB in aqueous solution. Oxidant (FeCl₃) to pyrrole varied in different molar ratios (2, 3, 4 and 5). It was found that increasing this ratio up to 4 increases PPy's conductivity. XRD, FTIR, and SEM were used to characterize Ppy. The conductive nature of Ppy was studied by I-V characteristics. The best conductive polymer is studied for the NH₃ gas response.

Fabrication of a nanoscale 2D PEDOT pattern via the combination of colloidal lithography and vapor phase polymerization for application in transparent, highly sensitive bending sensors

Recent advances in flexible, stretchable, and wearable electronics have necessitated the development of more diverse and complex device structures; high-resolution patterning strategies for conducting polymers are therefore urgently required to enable the fabrication of these devices. In this study, we report a nanoscale patterning strategy for conductive polymer films that utilizes a combination of vapor phase polymerization (VPP) and colloidal lithography. Here, hemispherical non-close-packed colloidal crystals are used as an effective lithographic mask for patterning oxidants on a substrate; subsequently, two-dimensional honeycomb-structured porous poly(3,4-ethylenedioxythiophene) (PEDOT) films are fabricated via VPP using the prepatterned oxidant. The resulting films closely resemble the morphology of the preceding oxidant structure; furthermore, the film porosity can be altered by adjusting the polymerization time. These patterned PEDOT films exhibit high transparency owing to the presence of voids, and high electrical sensitivity to bending stresses, which were concentrated in the narrow-patterned area. As the described fabrication methods are facile and reliable, this approach therefore provides an effective route for the fabrication of various conducting polymer frameworks in the micro- to nanoscale range.