A batch microfabrication of a microfluidic electrochemical COD sensor was fabricated. Miniaturization, low cost and the integration of three electrodes on the sensor chip. A shorter time (2 s) for organic matter digestion.
To address the demands for the large-scale application of electrochemical sensors in the field of environmental pollution monitoring, a novel silicon-based Ag/AgCl reference electrode (RE) was batch fabricated. The reference electrode consisted of a mini-chamber for saturated KCl solution storage and micro-nano-pores for Cl - exchange. The microstructures were fabricated via a two-step KOH wet etching on double sided oxidized and polished silicon wafer. The size of the micro-nano-pore diameters were precisely controlled by the etching time. The Ag/AgCl electrode was prepared on a Pyrex 7740 glass via silver lift-off process and electrochemical treatment. The silicon and glass substrates were joined by anodic bonding to form the finished Ag/AgCl micro- reference electrode. Compared with a commercial glass tube Ag/AgCl reference electrode, the micro-RE had the advantages of better reference potential stability, a small size, easy integration, and batch fabrication. The micro-RE was combined with a PbO 2 working electrode and a Pt counter electrode and applied to measure the glucose concentration in water samples. The results indicate that the novel micro-RE suitable for actual electrochemical detection, such as chemical oxygen demand (COD) measurements in water samples.
Chemical oxygen demand (COD) is an important indicator of the degree of organic pollution in water. However, the development of integrated and batch COD electrochemical sensors has always been challenging. In this study, a three-electrode integrated electrochemical sensor for the measurement of COD in surface water was evaluated. Using microfabrication with a microelectromechanical system (MEMS), the sensor was mass-produced and integrated with boron-doped diamond (BDD), Pt, and Ag/AgCl electrodes on the chip. The determination of glucose in optimal conditions provided a linear range from 5 to 200 mg L−1, a detection limit of 3.899 mg L−1, and satisfactory linearity (R2) of 0.998. As the sensor was fabricated by MEMS technology, good reproducibility was experimentally verified with relative standard deviations less than 4%, which suggests mass production of the sensor. The sensor was calibrated to be relatively stable in the presence of Cl− and NO2−. A low-cost, miniature (6 mm2), and stable COD sensor was designed using microfabrication technology that may be mass-produced to build a water quality detection network in the Internet of Things era.
This paper presents a comprehensive study of the structural optimization of polyimide-film (PI-film) capacitive humidity sensors, with a focus on enhancing their performance for application in new energy vehicles (NEVs). Given the critical role of humidity sensors in ensuring the safety and efficiency of vehicle operations─particularly in monitoring lithium-ion battery systems─the study explores the intricate relationship between the interdigitated electrode (IDE) dimensions and the PI-film thickness to optimize sensor responsiveness and reliability. Through a combination of COMSOL Multiphysics simulations (a powerful finite element analysis, solver, and simulation software) and experimental validation, the research identifies the optimal geometrical combination that maximizes the sensitivity and minimizes the response time. The fabrication process is streamlined for batch preparation, leveraging the spin-coating process to achieve consistent and reliable PI films. Extensive characterizations confirm the superior morphology, chemical composition, and humidity-sensing capabilities of the developed sensors. Practical performance tests further validate their exceptional repeatability, long-term stability, low hysteresis, and excellent selectivity, underpinning their suitability for automotive applications. The final explanation of the sensing mechanism provides a solid theoretical foundation for observed performance improvements. This work not only advances the field of humidity sensing for vehicle safety but also offers a robust theoretical and practical framework for the batch preparation of PI-film humidity sensors, promising enhanced safety and reliability for NEVs.
An electrochemical C(sp 3 )–C(sp) cross-coupling reaction of alkyl iodides, N -hydroxyphthalimide esters, and Katritzky salts with acetylenic sulfones is herein reported.
Free chlorine is one of the key water quality parameters in tap water. However, a free chlorine sensor with the characteristics of batch processing, durability, antibiofouling/antiorganic passivation and in situ monitoring of free chlorine in tap water continues to be a challenging issue. In this paper, a novel silicon-based electrochemical sensor for free chlorine that can self-clean and be mass produced via microfabrication technique/MEMS (Micro-Electro-Mechanical System) is proposed. A liquid-conjugated Ag/AgCl reference electrode is fabricated, and electrochemically stable BDD/Pt is employed as the working/counter electrode to verify the effectiveness of the as-fabricated sensor for free chlorine detection. The sensor demonstrates an acceptable limit of detection (0.056 mg/L) and desirable linearity (
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