It is becoming increasingly more important to provide a low-cost point-of-care diagnostic device with the ability to detect and monitor various biological and chemical compounds. Traditional laboratories can be time-consuming and very costly. Through the combination of well-established materials and fabrication methods, it is possible to produce devices that meet the needs of many patients, healthcare and medical professionals, and environmental specialists. Existing research has demonstrated that inkjet-printed and paper-based electrochemical sensors are suitable for this application due to advantages provided by the carefully selected materials and fabrication method. Inkjet printing provides a low cost fabrication method with incredible control over the material deposition process, while paper-based substrates enable pump-free microfluidic devices due to their natural wicking ability. Furthermore, electrochemical sensing is incredibly selective and provides accurate and repeatable quantitative results without expensive measurement equipment. By merging each of these favorable techniques and materials and continuing to innovate, the production of low-cost point-of-care sensors is certainly within reach.

The determination of hydrogen peroxide (H2O2) plays a crucial role in many industrial applications as well as clinical diagnoses. Electrochemical sensing techniques can provide a rapid, accurate, and simple approach to determine the level of hydrogen peroxide accurately. Recently, reduced graphene oxide (rGO) has been employed extensively to develop amperometric sensors for sensitive and selective detection of H2O2 because of its good catalytic activity, mass scalability, and cost-effectiveness. During the past decade, various reduction methods have been used to produce rGO for electrochemical sensing applications. Besides, these electrodes have been modified with functional materials to improve the response of the sensors. Depending on the used materials, characteristics and sensitivity of the sensors varied a lot. Also, the production method of rGO affects the performance of the electrochemical sensor and needs to be taken into account to correlate the results from the sensor with the physical and chemical properties of the sensing material. This article provides an insightful overview of the utilization of rGO in the developments of enzyme-free H2O2 electrochemical sensors. This review includes the recent advances in the area from both rGO production method and electrocatalyst performance. Also, the challenges and prospects were discussed in this review.

The development of various biosensors has revolutionized the healthcare industry by providing rapid and reliable detection capability. Printed circuit board (PCB) technology has a well-established industry widely available around the world. In addition to electronics, this technology has been utilized to fabricate electrical parts, including electrodes for different biological and chemical sensors. High reproducibility achieved through long-lasting standard processes and low-cost resulting from an abundance of competitive manufacturing services makes this fabrication method a prime candidate for patterning electrodes and electrical parts of biosensors. The adoption of this approach in the fabrication of sensing platforms facilitates the integration of electronics and microfluidics with biosensors. In this review paper, the underlying principles and advances of printed board circuit technology are discussed. In addition, an overview of recent advancements in the development of PCB-based biosensors is provided. Finally, the challenges and outlook of PCB-based sensors are elaborated.

This paper reports a novel disposable non-enzymatic hydrogen peroxide sensor fabricated using an inkjet printing method on paper. An electrochemical cell based on carbon nanotubes was patterned and printed on a paper substrate. Silver nanoparticles have been used as the catalyst for electrochemical reduction of H 2 O 2 . Moreover, a handheld multichannel potentiostat was developed in order to on-site determination of hydrogen peroxide. The device was characterized by performing simultaneous cyclic voltammetry measurements utilizing separate working electrodes at various scan rates. Using the presented system, we successfully measured the hydrogen peroxide concentration in an alkaline solution with the linear range of 1 μM-700 μM. Incorporating the paper-based enzyme-free sensor and portable readout system will result in accurate, reliable, cost effective, and on-site measurement of hydrogen peroxide in concentration as low as 1 μM.

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