Properties and customization of sensor materials for biomedical applications.

Low-power chemo- and biosensing devices capable of monitoring clinically important parameters in real time represent a great challenge in the analytical field as the issue of sensor calibration pertaining to keeping the response within an accurate calibration domain is particularly significant (1–4). Diagnostics, personal health, and related costs will also benefit from the introduction of sensors technology (5–7). In addition, with the introduction of Registration, Evaluation, Authorization, and Restriction of Chemical Substances (REACH) regulation, unraveling the cause–effect relationships in epidemiology studies will be of outmost importance to help establish reliable environmental policies aimed at protecting the health of individuals and communities (8–10). For instance, the effect of low concentration of toxic elements is seldom investigated as physicians do not have means to access the data (11)

Sensitivity Validation of EWOD Devices for Diagnosis of Early Mortality Syndrome (EMS) in Shrimp Using Colorimetric LAMP–XO Technique

Electrowetting-on-dielectric (EWOD) is a microfluidic technology used for manipulating liquid droplets at microliter to nanoliter scale. EWOD has the ability to facilitate the accurate manipulation of liquid droplets, i.e., transporting, dispensing, splitting, and mixing. In this work, EWOD fabrication with suitable and affordable materials is proposed for creating EWOD lab-on-a-chip platforms. The EWOD platforms are applied for the diagnosis of early mortality syndrome (EMS) in shrimp by utilizing the colorimetric loop-mediated isothermal amplification method with pH-sensitive xylenol orange (LAMP–XO) diagnosis technique. The qualitative sensitivity is observed by comparing the limit of detection (LOD) while performing the LAMP–XO diagnosis test on the proposed lab-on-a-chip EWOD platform, alongside standard LAMP laboratory tests. The comparison results confirm the reliability of EMS diagnosis on the EWOD platform with qualitative sensitivity for detecting the EMS DNA plasmid concentration at 102 copies in a similar manner to the common LAMP diagnosis tests

Copper Zinc Sulfide (CuZnS) Quantum Dot-Decorated (NiCo)–S/Conductive Carbon Matrix as the Cathode for Li–S Batteries

Sulfur composites consisting of electrochemical reactive catalysts/conductive materials are investigated for use in lithium–sulfur (Li–S) batteries (LSBs). In this paper, we report the synthesis, physicochemical and electrochemical properties of CuZnS quantum dots (CZSQDs) decorated with nickel–cobalt–sulfide ((NiCo)–S)) mixed with reduced graphene oxide (rGO)/oxidized carbon nanotube (oxdCNT) (rGO/oxdCNT) ((NiCo)–S@rGO/oxdCNT) composites. These composites are for the purpose of being the sulfur host cathode in Li–S batteries. The as-prepared composites showed a porous structure with the CZSQDs being uniformly found on the surface of the rGO/oxdCNT, which had a specific surface area of 26.54 m2/g. Electrochemical studies indicated that the (NiCo)–S@rGO/oxdCNT cells forming the cathode exhibited a maximum capacity of 1154.96 mAhg−1 with the initial discharge at 0.1 C. The smaller size of the CZSQDs (~10 nm) had a positive effect on the CZSQDs@(NiCo)–S@rGO/oxdCNT composites in that they had a higher initial discharge capacity of 1344.18 mAhg−1 at 0.1 C with the Coulombic efficiency being maintained at almost 97.62% during cycling. This latter property is approximately 1.16 times more compared to the absence of the Cu–Zn–S QD loading. This study shows that the CuZnS quantum dots decorated with a (NiCo)–S@rGO/oxdCNT supporting matrix-based sulfur cathode have the potential to improve the performance of future lithium–sulfur batteries

Graphene-based flexible circuit on cotton fabric using wax patterning method

With recent development in the field of wearable devices for biomedical applications, various studies have been conducted on the fabrication of electrically conductive circuit on flexible substrate materials such as paper or textile. In this project, we propose the fabrication of electrically conductive circuit on cotton fabric using simple wax patterning method. Using this method, hydrophilic and hydrophobic regions were patterned on the fabric and graphene-poly (3,4-ethylenedioxythiophene): poly (styrenesulfonic acid) (graphene-PEDOT:PSS) ink was deposited on the hydrophilic region using pipetting method. Conductive lines with higher conductance were fabricated by multiple deposition of the conductive ink and electronic components were successfully attached on the fabric to develop a simple fully functional flexible circuit

Violet Laser Treatment of Nitrogen-Doped Reduced Graphene Oxide Electrodes and KOH Electrolytes Containing <i>p</i>‑Phenylenediamine for High-Performance Supercapacitors

The electrical conductivity and capacitive behavior of supercapacitors (SCs) were found to be improved by the synergistic effects of the violet laser treatment (VLT) of nitrogen-doped reduced graphene oxide (N-rGO) as an electrode and 1.5% (w/v) p-phenylenediamine (PPD)-containing KOH as a redox electrolyte. The SC employing VLT treatment on the N-rGO electrode with 2 M KOH (N-rGO-V) represented a greater specific capacitance of up to 263.6 F g–1 compared to N-rGO in the same electrolyte, which was 232.2 F g–1 at 0.25 A g–1. To further improve the charge-storage ability, the SC using the VLT treatment on the N-rGO electrode with the PPD addition into 2 M KOH (N-rGO-V-PPD) revealed the highest specific capacitance, reaching 593.7 F g–1 at 0.25 A g–1 or 28.6% compared to N-rGO in the same redox electrolyte (N-rGO-PPD). Furthermore, the capacitance retention after 10,000 cycles of N-rGO-V-PPD remained at 62% (265 F g–1 at 100 mV s–1), which is still significantly higher than that of other samples, and the VLT technique provided a lower self-discharge rate. According to the physical characterizations, N-rGO-V-PPD has a rougher and larger surface area due to the exfoliated graphene oxide sheets and has a modest increase in the number of quinone/carbonyl functional groups in the graphene material, resulting in better electrical conductivity. All of these could be contributing factors to the performance improvement. Lastly, PPD provides redox mediators such as H+ and e– in the redox electrolyte, which are anticipated to improve the charge storage