A fully handwritten-on-paper copper nanoparticle ink-based electroanalytical sweat glucose biosensor fabricated using dual-step pencil and pen approach

Lancet-free and label-free diagnostics of glucose in sweat using Zinc Oxide based flexible bioelectronics

Copper nanoparticle (NP) inks offer lower cost conductors compared with the more common silver conductors used for flexible electronics applications. However, oxidation occurs during conventional oven-curing limiting their use. This paper reports screen/inkjet printed copper conductors, cured using a laser, on flexible Kapton (Polyimide), PET (Polyethylene terephthalate), paper and polyester/cotton fabric in ambient air. The results show that copper NP inks can be laser sintered without oxidation or damage to these flexible substrates.

Core-shell structured gold nanorods on thread-embroidered fabric-based microfluidic device for Ex Situ detection of glucose and lactate in sweat

WS2/CuO-based non-enzymatic sensor for the detection of glucose in sweat.

Dual detection of human motion and glucose in sweat with polydopamine and glucose oxidase doped self-healing nanocomposite hydrogels

For deposition of two-dimensional materials (e.g., graphene) on a substrate, self-aggregation and poor anchor strength are still issues. Herein, the GaN nanowire (NW) substrate was employed for electrochemical deposition of reduced graphene oxide (rGO) with satisfying dispersion uniformity and anchor strength. The deposited rGO exhibited flake morphology without agglomeration. Moreover, PtAu and rGO can be simultaneously and uniformly deposited on the GaN NW substrate to realize a PtAu–rGO/GaN electrochemical sensor for glucose detection. In comparison with deposition of PtAu–rGO on a stainless steel (SS) substrate (i.e., PtAu–rGO/SS), PtAu–rGO/GaN demonstrated much higher sensitivity and long-term stability, owing to better dispersion and anchor strength on GaN NW. In addition, with decoration of glucose oxidase (GOx), the GOx/PtAu–rGO/GaN sensor can be used for detecting glucose in human sweat with a low limit of detection of 5 μM, a wide linear detection range of 5 μM–12 mM, and high long-term stability, which indicates that GOx/PtAu–rGO/GaN sensor is promising for noninvasive glucose detection.

The formation of conductive micropatterns via laser direct writing using metal nanoparticle ink was studied toward 3D interconnection. Copper (Cu) micropatterns were fabricated by laser irradiation on a precursor film prepared via spin-coating of a Cu nanoparticle ink on a substrate. A focused laser beam was scanned on the copper nanoparticle film using a xyz motion control stage. The solution etching of the film after laser scanning gave a Cu micropattern via removing unirradiated area. A copper wiring with a hollow structure was fabricated by layer-by-layer 3D printing, where the spin-coating of Cu nanoparticle ink and the laser direct writing were repeated alternatively.

A sample-to-answer, wearable cloth-based electrochemical sensor (WCECS) for point-of-care detection of glucose in sweat

Flexible electrochemicalsensors based on noninvasive materialscan continuously monitor blood glucose levels in sweat, making themideal for personal diabetes management intelligent devices. It isnecessary to construct sweat glucose electrochemical sensors thathave the ability to both adjust to human skin and reliably monitor.We first synthesized nickel/cobalt metal–organic frameworkmaterial (Ni/Co-MOF) nanosheets via a solvent-thermal approach. Then,an oil-based polyurethane (OPU)/polypropylene spun-bonded nonwovenfabric (PPSF) was obtained by coating the surface of PPSF. Silver/silverchloride (Ag/AgCl) paste and conductive carbon (C) paste were printedlayer-by-layer on the surface of the OPU/PPSF by screen printing,followed by the immobilization of Ni–Co/MOF nanosheets on theworking area using a Nafion solution to form a Ni/Co-MOF@OPU/PPSFflexible glucose sensor for continuous monitoring of glucose in sweat.This Ni/Co-MOF@OPU/PPSF flexible glucose sensor retained the highelectrocatalytic activity of Ni/Co-MOF for glucose oxidation and exhibitedhigh sensitivity (159.9 μA/mM·cm2), low limitof detection (LOD) (2 μM), and a wide linearly glucose-monitoringrange (10 μM–1 mM). Compared to other nonenzymatic sensors,our Ni/Co-MOF@OPU/PPSF flexible glucose sensor has better immunitythan other substances present in sweat. Meanwhile, the Ni/Co-MOF@PPSFflexible glucose sensor not only monitors the glucose in sweat atdifferent body temperatures but also maintains good mechanical flexibilityand stable electrochemical properties under bending conditions. Itis suggested that our flexible glucose sensor can be used for continuousmonitoring of glucose in human sweat. Overall, our glucose sensorcan be used for the continuous monitoring of glucose in human sweat.

Diabetes, a metabolic disorder, has become a major health problem in the world. According to WHO report, the number of patients is projected to 300 million in 2025. Therefore, the need of glucose detection is extremely important to the patients suffering from diabetes. Glucose oxidase (GOx) has been extensively used to construct amperometric biosensors for glucose detection owing to its high selectivity and sensitivity to glucose. However, GOx-based biosensors suffer from a stability problem due to the fundamental feature of enzymes. Therefore, it requires a need for enzyme-free glucose sensors. During last two decades, considerable attention has been paid to develop enzyme-free electrodes. Precious metals, metal alloys, and metal nanoparticles are extensively studied for advancement of non-enzymatic glucose sensors. Therefore, the need of a cost-effective, sensitive, and reliable enzyme-free glucose sensor is in great demand. In recent years, noble metal nanoparticles have found immense interest by researchers due to their potential in label-free forms of biological and chemical sensors. The high capability of these sensors is due to the novel properties of noble metal nanostructured arrays, for instance, high surface to volume ratio, localized surface plasmon resonance, excellent conductivity and anomalous transmission, and reflection of light. The amperometric technique is most widely used tool in the sensing of glucose. On the other side, some LSPR sensors are also reported which showed good sensitive to the changes in refractive index occurring at a metal/dielectric interface. Some researchers also studied fiber-optic-based glucose sensor which was based on the attenuated total reflection phenomenon. Enzymatic and non-enzymatic sensors of silver, gold, and copper nanoparticles are discussed in details in the chapter. The fabrication of glucose sensors has also been discussed with keeping in view the interest of the researchers. The objective of this chapter is to cover the bare and modified/composites of metal nanoparticles as glucose sensor. The most recent as well as conventional fabrication methods are discussed in detail. The linearity range and limit of detection of the glucose sensors are described in detail to justify the fabrication process. The chapter will provide in-depth review of metal nanoparticles-based glucose sensors which would be beneficial to all researchers, scientists, engineers, and students who are in direct contact of developing and using glucose sensors. It is hoped that the chapter will bridge the common gap between the research literature and standard textbooks. The material in this chapter emphasizes on developments of sensitive, rapid, and cheap systems for identification of glucose. The fabrication techniques of metal nanoparticles as glucose sensor are also studied in connection with different methodologies like SPR, SERS, electrochemical, and paper based devices.

In this study, a flexible and wearable chemiresistive biosensor (FWCB) is developed for the real‐time analysis of glucose in sweat on the human skin surface based on a novel detection strategy of p‐type reduced graphene oxide (rGO) sensing film, which met the requirements of rapid, nondestructive testing. The proposed FWCB is fabricated in the form of interdigital electrodes (IEs) made of laser‐induced graphene (LIG) synthesized by the laser inducing of a polyimide (PI) film. Additionally, a semiconducting rGO sensing film modified on the surface of IEs is synthesized by thermal reduction of graphene oxide (GO), which is functionalized with glucose oxidase (GOx) by chemical cross‐linking to obtain GOx/FWCB. Moreover, the key parameters for FWCB fabrication are optimized, and the sensing strategy of the proposed GOx/FWCB is also investigated. The results show that the proposed GOx/FWCB can be used for the detection of glucose in the range of 0.01–3.0 mM with satisfactory selectivity, and the limit of detection (LOD) is calculated to be as low as 0.8 µM (S/N = 3). These dramatic advantages endow the proposed FWCB with broad application prospects in the field of portable, wearable, and real‐time detection of glucose in human sweat for health monitoring.

Realizing high-performance glucose sensing in sweat: Synergistic use of nickel oxide nanosheets as photoelectrodes and the masking effect of Mo-POM for photoelectrochemical detection

Continuous painless glucose monitoring is the greatest desire of more than 422 million diabetics worldwide. Therefore, new non-invasive and convenient approaches to glucose monitoring are more in demand than other tests for microanalytical diagnostic tools. Besides, blood glucose detection can be replaced by continuous glucose monitoring of other human biological fluids (e.g. sweat) collected non-invasively. In this study, a skin-attachable and stretchable electrochemical enzymatic sensor based on ZnO tetrapods (TPs) and a new class of 2D materials - transition metal carbides, known as MXene, was developed and their electroanalytical behavior was tailored for continuous detection glucose in sweat. The high specific area of ZnO TPs and superior electrical conductivity of MXene (Ti3C2Tx) nanoflakes enabled to produce enzymatic electrochemical glucose biosensor with enhanced sensitivity in sweat sample (29 μA mM−1 cm−2), low limit of detection (LOD ≈ 17 μM), broad linear detection range (LDR = 0.05–0.7 mM) that satisfices glucose detection application in human sweat, and advanced mechanical stability (up to 30% stretching) of the template. The developed skin-attachable stretchable electrochemical electrodes allowed to monitor the level of glucose in sweat while sugar uptake and during physical activity. Continuous in vivo monitoring of glucose in sweat obtained during 60 min correlated well with data collected by a conventional amperometric blood glucometer in vitro mode. Our findings demonstrate the high potential of developed ZnO/MXene skin-attachable stretchable sensors for biomedical applications on a daily basis.

Flexible hydrophilic-hydrophobic array detection patch integrated with Au NPs/Cu-TCPP(Fe) biomimetic cascade catalysis reactions for enzyme-free sweat glucose monitoring.

Copper nanoparticle inks have drawn much attention since they have the potential to constitute an alternative cost‐effective solution than other noble metals nanoparticle inks such as Ag for indium tin oxide (ITO)‐free printed electronic applications. Our research and development efforts have produced high conductivity copper nanoparticle inks which have excellent jetting and printing properties resulting in high quality inkjet‐printed (IJP) Cu nanoparticle‐based metal grids. We present ITO‐free, Si‐PCPDTBT: PC[70]BM organic photovoltaics (OPVs) processed in ambient low‐cost fabrication conditions comprising for the first time embedded and non embedded inkjet‐printed copper grid/Poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the bottom electrode with power conversion efficiencies (PCE) of 2.56 and 3.35%, respectively. The results of the ITO‐free OPVs using inkjet‐printed Cu nanoparticle current collecting grids are discussed relevant to reference ITO‐based OPVs with PCE of 4.92%.