DisposablePrinted Electrode Made with Chinese Shellacand Carbon Black for Melatonin Detection

Homemade screen-printed electrodes (SPEs) were developed using conductive inks based on graphite and alkyd resin. The SPEs were optimized by varying the graphite content (50% and 60% by mass) with the incorporation of toluene (T) as a solvent into the conductive inks to improve homogeneity. The SPEs were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). The optimized SPE (SPE 50:50 T) demonstrated higher peak currents and a significant decrease in charge transfer resistance (R ct) from 619 ± 8 Ω to 283 ± 5 Ω compared to the SPE without toluene (SPE 50:50). Additionally, SPE 50:50 T exhibited a more homogeneous surface and an electroactive area 1.4 times larger than that of the SPE 50:50. To enhance sensitivity, SPE 50:50 T was modified with a dispersion of functionalized multiwalled carbon nanotubes (MWCNTs) in ethanol (1 g L−1) and applied to the electroanalytical determination of diuron pesticide (C9H10Cl2N2O). The results showed that the oxidation peak potential was approximately 0.75 V vs. Ag/AgCl in pH 2.0 buffer solution, which is lower than the reported literature value of approximately 1.10 V. The linear concentration range was between 1.07 µmol L−1 and 7.51 µmol L−1 using differential pulse voltammetry (DPV) in pH 2.0 solution, with limits of detection (LOD) and quantification (LOQ) of 0.112 µmol L−1 and 0.373 µmol L−1, respectively. Recovery tests in samples of seawater and grape juice were successfully performed.

Carbon black assisted tailoring of Prussian Blue nanoparticles to tune sensitivity and detection limit towards H2O2 by using screen-printed electrode

Recent advancements in conductive inks, multiplex systems, and innovative treatments have enhanced electrochemical sensor functionality. In this context, lab-made screen-printed electrodes (SPEs) offer a cost-effective alternative to conventional electrodes, with various treatments improving their analytical performance. CO₂ laser-scribing, a low-cost pyrolysis method, converts organic substrates into conductive materials, improving conductivity and performance. In this study, a dual working-electrode SPE was fabricated and treated via CO₂ laser-scribing. Optimizing laser power, Z-distance, and scan rate led to significant increases in current magnitude and electroactive area. Morphological analysis using scanning electron microscopy and contact angle measurements confirmed a new conductive layer with greater thickness and hydrophobicity, likely carbon-based. The laser-treated SPE enabled sensitive detection of propranolol (PRNL), a β-blocker banned in sports. Using differential pulse voltammetry, the sensors exhibited a linear range from 5.0 to 1000 μmol l−1, with limits of detection of 0.98 and 1.00 μmol l−1. Recovery in tap water ranged from 95.6% to 109%. This study highlights the potential of CO₂ laser-treated SPEs for PRNL detection in environmental and real-sample contexts.

Development of silver/carbon screen-printed electrode for rapid determination of vitamin C from fruit juices

Gatifloxacin is the drug of choice in the treatment of community-acquired pneumonia in many studies. However, cytotoxicity was reported at its high doses. Therefore, gatifloxacin overdose monitoring is very important. In this sense, there is a need for developing fast and cheap analytical methods for gatifloxacin quantitation in biological fluids. In the present study, a novel detection strategy involving gatifloxacin quantification in urine samples was developed. The approach has been adapted for the use of solid inner contact and rapid disposal screen-printed graphitic carbon electrodes exhibiting high sensitivity toward gatifloxacin without interference from several ions found in urine samples. The developed electrodes showed linear responses in the concentration ranges from 1 × 10–5 to 0.01 and 1 × 10–6 to 0.01 M for a solid contact glassy carbon ion selective electrode (GSC) and a screen printed electrode (GSP), respectively. The analytical applicability of the approach was demonstrated through recovery experiments of gatifloxacin trace concentrations in urine. GSP ion selective electrode (ISE) was found to have superior stability, shorter response time, higher selectivity and sensitivity and longer shelf life compared to GSC ISE. GSP ISE showed the best Nernestian slope as well as the lowest detection limit. Moreover, the inherent advantages of screen-printed electrodes technology (low sample consumption, low cost and point of care testing) make this methodology very attractive in this field. As a result, the developed ISEs can be the best choice for in-line determination of gatifloxacin in urine samples to detect overdose intake and its associated symptoms as well as for quality-control laboratories without pre-treatment or separation steps.

There has been a growing interest in portable, flexible, and disposable electrochemical sensors in recent years due to their low cost, simplicity, and excellent analytical performance. Despite significant advancements in the field, the demand for low-cost, high-performance electrodes remains challenging. In this study, a flexible and disposable sensor with low-cost and simple fabrication was developed as a sustainable approach. Conductive ink was prepared using nail polish and graphite powder, while polyethylene terephthalate from recycled beverage bottles was repurposed as the sensor substrate. The fabricated electrode was characterized using differential pulse voltammetry (DPV), cyclic voltammetry, scanning electron microscopy, Fourier-transform infrared, and contact angle. The developed flexible screen-printed electrode (FSPE) was employed for the simultaneous detection of acetaminophen and caffeine (CAF). Using the DPV technique, a linear detection range of 50–2000 μM was achieved for both analytes, with limits of detection of 6.53 μM for ACE and 3.10 μM for CAF. Moreover, the FSPE was successfully applied for the simultaneous and individual detection of acetaminophen and caffeine in commonly available commercial pharmaceuticals. A cost analysis revealed that the production cost per FSPE unit is $0.436, considering the raw material costs for producing 100 units.

Extended coverage of screen-printed graphite electrodes by spark discharge produced gold nanoparticles with a 3D positioning device. Assessment of sparking voltage-time characteristics to develop sensors with advanced electrocatalytic properties

Introduction Gas sensors have been received extensive attentions due to the critical roles of various gases in industry, environmental monitoring and agriculture. A variety of gas sensing approaches has been developed such as gas chromatography, optical sensing, metal oxide semiconductor-based sensing and electrochemical sensing. Compared to other methods, electrochemical method features high sensitivity, low detection limit, good reproducibility and wide detection range, which has been explored for applications in real world. As a typical electrochemical device, screen printed electrodes (SPEs) can be easily and massively fabricated with good integration and low cost. Also, the easily tunable ink composition is another intriguing feature for specific applications. However, screen printed carbon electrodes (SPCEs) have inferior electrochemical catalysis to noble metal-based sensors despite of its low cost. To further improve the electrochemical performance of SPCEs for gas sensing, nanomaterials are considered as a promising alternative due to its high catalysis, fast electron transfer and large active surface area. MXene is a new class of two-dimensional materials such as Ti3C2X, in which X indicates oxygen- and fluorine-containing functional groups. MXene demonstrates outstanding electrochemical features with excellent catalytic ability. However, MXene materials can easily induce spontaneous oxidation reaction with oxygen and water due to its inherent feature. Therefore, nanocomposites with MXene and metal nanostructures are introduced to improve the stability and further enhance the catalytic performance. In this paper, a screen-printed carbon electrode (SPCE) with self-assembled AuNPs@MXene modification was developed for high sensitive electrochemical gas detection. The sensor performance was compared and evaluated with different concentrations of oxygen using cyclic voltammetry and chronoamperometry. Experimental Compressed air (21% O2) and nitrogen were used as the target gas and balancing gas, respectively. Room temperature ionic liquids 1-butyl-1-methylpyrrolidinium bis-(trifluoromethylsulfonyl)-imide ([C4mpy][NTf2], Aladdin, China) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6], Acros Organics, USA) were used as the supporting electrolyte by drop-casting on the sensor surface. Ti3C2X powders were synthesized by using HF to etch Ti3AlC2 particles as reported in the literature [1]. Gold nanoparticles were synthesized by using trisodium citrate and chloroauric acid as reported in the literature [2]. All chemicals were used as received without further purification. Screen-printed carbon electrodes were purchased from Zensor R&D Inc. A gas blender (MCQ100, Italy) was used for gas mixing, and the total gas flow rate was set constant as 200 standard cubic centimeter per minute (SCCM).An electrochemical analyzer CHI 1030 was used for electrochemical tests using cyclic voltammetry (CV) and constant potential chronoamperometry. Results The bare SPCE was first tested in 21% O2 and nitrogen using cyclic voltammetry, and a pair of reduction peak and oxidation peak can be apparently observed, validating the catalytic ability of carbon-based sensors for gas sensing. Two different RTILs were tested using as the electrolyte, and the results indicate that the sensor using [C4mpy][NTf2] presents higher current response and sensitivity. The sensing performance of bare SPCE, MXene modified SPCE and AuNPs@MXene modified SPCE was compared using CV and chronoamperometry, and AuNPs@MXene modified SPCE exhibits the highest current response and sensitivity due to the synergetic catalytic effect of MXene and AuNPs. The AuNPs@MXene modified SPCE was tested with different oxygen concentration, validating that the sensor has very high sensitivity, wide linear range, low detection limit and good reproducibility. Thus, the sensor can be a promising device for practical gas sensing applications in the real world.

The use of disposable screen-printed electrodes (SPEs) has extraordinarily grown in the last years. In this paper, conductive inks from scrapped SPEs were removed by acid leaching, providing high value feedstocks suitable for the electrochemical deposition of Ag, Pt and Ag core-Pt shell-like bimetallic (AgPt) nanoparticles, onto screen-printed carbon electrodes (ML@SPCEs, M = Ag, Pt or AgPt, L = metal nanoparticles from leaching solutions). ML@SPCEs were characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The results were compared to those obtained when metal nanoparticles were synthesised using standard solutions of metal salts (MS@SPCEs). Both ML@SPCEs and MS@SPCEs exhibited similar cyclic voltammetric patterns referred to the electrochemical stripping of silver or the adsorption/desorption of hydrogen/anions in the case of platinum, proving leaching solutions extremely effective for the electrodeposition of metallic nanoparticles. The use of both ML@SPCEs and MS@SPCEs proved effective in enhancing the sensitivity for the detection of H2O2 in phosphate buffer solutions (pH = 7). The AgPtL@SPCE was used as proof of concept for the validation of an amperometric sensor for the determination of H2O2 within laundry boosters and antiseptic samples. The electrochemical sensor gave good agreement with the results obtained by a spectrophotometric method with H2O2 recoveries between 100.6% and 106.4%.

Using low-cost disposable immunosensor based on flexible PET screen-printed electrode modified with carbon black and gold nanoparticles for sensitive detection of SARS-CoV-2

Liquid metal or liquid metal microparticles (LMP) based conductive inks, though promising for fabrication of circuits for use in soft and stretchable electronics, are constrained by a few drawbacks such as need for encapsulation, need for sintering to induce conductivity, and smearing. To address these issues, herein, a stretchable conductive composite ink is developed by combining LMPs with carbon black (CB) in highly entangled polysiloxane elastomer. LMP‐dispersed elastomer lacks conductivity because of its non‐percolated network, however, the CB can interconnect LMPs to act as a bridge, thereby imparting conductivity to the elastomer. Due to presence of fluidic LMPs, the LMPs‐dispersed elastomer lies in soft regime with initial conductivity of 5.6 S m−1, aided by the presence of CB in the interstitial spaces between the LMPs. The highly entangled molecular network of the encapsulating elastomer endows the resulting composite with high stretchability (≈286%) and softness (0.648 MPa) and its long pot life enables rheological modulation of the ink to achieve pressure‐driven direct printed non‐smearing traces. The LMPs‐based conductive ink developed in this work is expected to be further utilized in the fabrication of soft robotics and electronic skin and integrated into electronic modules by facile direct 3D printing.

Three types of conductive inks, including Ceres, Acheson carbon inks, and Ag/AgCl ink, were utilized to fabricate screen-printed electrodes (SPEs) on a 0.4 mm thick polyethylene terephthalate substrate using a screen-printing technique. To enhance the electrical conductivity, the printed electrodes were cured at 80°C for 90 minutes. The basic electrochemical properties of the self-made SPEs using these conductive inks were determined, evaluated, and compared with commercial SPEs from Metrohm. Although the electroactive surface areas of the self-made SPEs were not significantly different from those of the commercial SPEs, the heterogeneous electron transfer rates on the surfaces of self-made SPEs using Ceres and Acheson inks were inferior to those of the commercial SPEs. However, after pre-condition by applying a potential of +1.2 V for 180 s in a 2 M Na2CO3 solution, the electrochemical properties of the self-made SPEs, including the active surface areas and heterogeneous electron transfer rates, were significantly improved and became better than those of the commercial SPEs.

Decentralization of on-site and in-site trace metal analysis has been a key topic over the last 30 years, owing to the increasing need for environmental protection as well as industrial and health-based field applications. In trace (and ultratrace) metal analysis, electrochemical stripping analysis with mercury (or bismuth) screen-printed film electrodes has shown a fast growth in popularity thanks to the good limits of detection, the ease of application in the field, and the low cost. Moreover, the availability of new wall-jet flow cells has opened the opportunity for their use in in situ industrial monitoring. The analytical figures of merit in stripping voltammetry with screen-printed electrodes (SPEs) under decentralized conditions and/or with sensor arrays are heavily affected by some analytical factors, primarily the presence of a pseudo-reference electrode, the efficiency of mass transport during the preconcentration step, and the need for external calibration. A careful model investigation of the analytical parameters for an efficient use of SPEs in decentralized conditions has been undertaken and discussed. Different instrumental approaches were investigated, comparing optimized batch conditions and flow cell operation under either continuous flow or stopped-flow sample injection. The stripping efficiency under wall-jet flow conditions was found to be high and comparable to that in batch conditions, leading to sub-ppb (μg/L) limit of detection (LOD) figures. Finally, external calibration in stripping voltammetry was studied as a viable alternative to conventional standard addition quantitation. Results showed, indeed, that external calibration was demonstrated to be reliable for quantitation of Pb and Cd in real water samples.

As a key material for printed electronics, conductive inks have received extensive attention. Conductive polymer polyaniline (PANI) as a conductive filler has the advantages of easy synthesis, low cost, high conductivity and good environmental stability, which provides a new way for the application and development of conductive inks. In order to fully grasp the progress of PANI conductive ink and its application, this paper comprehensively analyzes the research progress, application and preparation process of PANI conductive ink based on the literature and research work of conductive polymer ink in recent years. It is pointed out that the main development direction of PANI conductive ink is to compound PANI with other functional materials (such as metals and carbon materials) to form a stable, efficient, low-cost and environmentally friendly composite conductive ink, and the application prospect of PANI conductive ink is proposed.KeywordsConductive polymerPANIConductive inkPrinted electronics

Novel and flexible disposable laser-induced graphene (LIG) sensors modified with graphene conductive inks have been developed for dopamine and interleukin-6 (IL-6) detection. The LIG sensors exhibit high reproducibility (relative standard deviation, RSD = 0.76%, N = 5) and stability (RSD = 4.39%, N = 15) after multiple bendings, making the sensors ideal for wearable and stretchable bioelectronics applications. We have developed electrode coatings based on graphene conductive inks, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (G-PEDOT:PSS) and polyaniline (G-PANI), for working electrode modification to improve the sensitivity and limit of detection (LOD). The selectivity of LIG sensors modified with the G-PANI ink is 41.47 times higher than that of the screen-printed electrode with the G-PANI ink modification. We have compared our fabricated bare laser-engraved Kapton sensor (LIG) with the LIG sensors modified with G-PEDOT (LIG/G-PEDOT) and G-PANI (LIG/G-PANI) conductive inks. We have further compared the performance of the fabricated electrodes with commercially available screen-printed electrodes (SPEs) and screen-printed electrodes modified with G-PEDOT:PSS (SPE/G-PEDOT:PSS) and G-PANI (SPE/G-PANI). SPE/G-PANI has a lower LOD of 0.632 μM compared to SPE/G-PEDOT:PSS (0.867 μM) and SPE/G-PANI (1.974 μM). The lowest LOD of the LIG/G-PANI sensor (0.4084 μM, S/N = 3) suggests that it can be a great alternative to measure dopamine levels in a physiological medium. Additionally, the LIG/G-PANI electrode has excellent LOD (2.6234 pg/mL) to detect IL-6. Also, the sensor is successfully able to detect ascorbic acid (AA), dopamine (DA), and uric acid (UA) in their ternary mixture. The differential pulse voltammetry (DPV) result shows peak potential separation of 229, 294, and 523 mV for AA-DA, DA-UA, and UA-AA, respectively.