Why PEDOT:PSS Should Not Be Used for Raman Sensing of Redox States (and How It Could Be)

Enhanced Microstructural Uniformity in Sulfuric-Acid-Treated Poly(3,4-Ethylenedioxythiophene):Poly(Styrene Sulfonate) Films Using Raman Map Analysis

Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films have emerged as potential alternatives to indium-tin oxide as transparent electrodes in optoelectronic devices because of their superior transparency, flexibility, and chemical doping stability. However, pristine PEDOT:PSS films show low conductivities because the insulating PSS-rich domains isolate the conductive PEDOT-rich domains. In this study, the conductivities and corresponding spatially resolved Raman properties of PEDOT:PSS thin films treated with various concentrations of H2SO4 are presented. After the PEDOT:PSS films are treated with the H2SO4 solutions, their electrical conductivities are significantly improved from 0.5 (nontreated) to 4358 S cm-1 (100% v/v). Raman heat maps of the peak shifts and widths of the Cα═Cβ stretching mode are constructed. A blueshift and width decrease of the Cα═Cβ Raman mode in PEDOT are uniformly observed in the entire measurement area (20 × 20 µm2), indicating that microstructural transitions are successfully accomplished across the area from the coiled to linear conformation and high crystallinity upon H2SO4 treatment. Thus, it is proved that comprehensive Raman map analysis can be easily utilized to clarify microstructural properties distributed in large areas induced by various dopants. These results also offer valuable insights for evaluating and optimizing the performance of other conductive thin films.

Multifunctional laser-induced graphene circuits and laser-printed nanomaterials toward non-invasive human kidney function monitoring

Faced with the increasing prevalence of chronic kidney disease (CKD), portable monitoring of CKD-related biomarkers such as potassium ion (K+), creatinine (Cre), and lactic acid (Lac) levels in sweat has shown tremendous potential for early diagnosis. However, a rapidly manufacturable portable device integrating multiple CKD-related biomarker sensors for ease of sweat testing use has yet to be reported. Here, a portable electrochemical sensor integrated with multifunctional laser-induced graphene (LIG) circuits and laser-printed nanomaterials based working electrodes fabricated by fully automatic laser manufacturing is proposed for non-invasive human kidney function monitoring. The sensor comprises a two-electrode LIG circuit for K+ sensing, a three-electrode LIG circuit with a Kelvin compensating connection for Cre and Lac sensing, and a printed circuit board based portable electrochemical workstation. The working electrodes containing Cu and Cu2O nanoparticles fabricated by two-step laser printing show good sensitivity and selectivity toward Cre and Lac sensing. The sensor circuits are fabricated by generating a hydrophilic-hydrophobic interface on a patterned LIG through laser. This sensor recruited rapid laser manufacturing and integrated with multifunctional LIG circuits and laser-printed nanomaterials based working electrodes, which is a potential kidney function monitoring solution for healthy people and kidney disease patients.

From Water for Water: PEDOT:PSS-Chitosan Beads for Sustainable Dyes Adsorption

This study investigates the viability of developing chitosan-based hydrogels derived from waste shrimp shells for the removal of methylene blue and methyl orange, thereby transforming food waste into advanced materials for environmental remediation. Despite chitosan-based adsorbents being conventionally considered ideal for the removal of negative pollutants, through targeted functionalization with poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) at varying concentrations, we successfully enhance the hydrogels' efficacy in also adsorbing positively charged adsorbates. Specifically, the incorporation of PEDOT:PSS at a concentration of 10% v/v emerges as a critical factor in facilitating the robust adsorption of dyes. In the case of the anionic dye methyl orange (MO, 10-5 M), the percentage of removed dye passed from 47% (for beads made of only chitosan) to 66% (for beads made of chitosan-PEDOT:PSS 10%), while, in the case of the cationic dye methylene blue (MB, 10-5 M), the percentage of removed dye passed from 52 to 100%. At the basis of this enhancement, there is an adsorption mechanism resulting from the interplay between electrostatic forces and π-π interactions. Furthermore, the synthesized functionalized hydrogels exhibit remarkable stability and reusability (at least five consecutive cycles) in the case of MB, paving the way for the development of cost-effective and sustainable adsorbents. This study highlights the potential of repurposing waste materials for environmental benefits, introducing an innovative approach to address the challenges regarding water pollution.