As atenolol overdosing can lead to severe health complications, the fast detection of atenolol intake in point-of-care settings is highly desirable. The recent advancement of redox analytical methodologies has facilitated the efficacious quantification of these compounds for drug analysis, but their performance is still limited to present challenges in practical applications. This study addresses these challenges by controlling the electropolymerization of polydopamine (PDA) on highly porous laser-induced graphene (LIG) electrodes with enhanced electrochemical redox activity activities for the detection of drug molecules such as atenolol, with minimized interferesnce with the other active substances to induce variation of electrochemical behavior. The enhanced sensitivity of atenolol is attributed to the superhydrophilicity and more active surface sites and -NH2 groups in the PDA polymer through a controlled polymerization process. Moreover, the simulation results further reveal that highly sensitive sensing of atenolol molecules relies on optimal adsorption of atenolol molecule on dopamine or dopaminequinone structural units. The resulting sensors with high repeatability and reproducibility can achieve a low detection limit of 80 µM and a sensitivity of 0.020± 0.04 µA/µM within a linear range from 100 to 800 µM. The materials and surface chemistry in the electrode design based on highly porous LIG provide insights into the integration and application of future scalable and cost-effective electrochemical sensors for use in point-of-care or in-field applications.
Gas-sensitive semiconducting nanomaterials (e.g., metal oxides, graphene oxides, and transition metal dichalcogenides) and their heterojunctions hold great promise in chemiresistive gas sensors. However, they often require a separate synthesis method (e.g., hydrothermal, so-gel, and co-precipitation) and their integration on interdigitated electrodes (IDE) via casting is also associated with weak interfacial properties. This work demonstrates in situ laser-assisted synthesis and patterning of various sensing nanomaterials and their heterojunctions on laser-induced graphene (LIG) foam to form LIG composites as a flexible and stretchable gas sensing platform. The porous LIG line or pattern with nanomaterial precursors dispensed on top is scribed by laser to allow for in situ growth of corresponding nanomaterials. The versatility of the proposed method is highlighted through the creation of different types of gas-sensitive materials, including transition metal dichalcogenide (e.g., MoS2), metal oxide (e.g., CuO), noble metal-doped metal oxide (e.g., Ag/ZnO) and composite metal oxides (e.g., In2O3/Cr2O3). By eliminating the IDE and separate heaters, the LIG gas sensing platform with self-heating also decreases the device complexity. The limit of detection (LOD) of the LIG gas sensor with in situ synthesized MoS2, CuO, and Ag/ZnO to NO2, H2S, and trimethylamine (TMA) is 2.7, 9.8, and 5.6 ppb, respectively. Taken together with the high sensitivity, good selectivity, rapid response/recovery, and tunable operating temperature, the integrated LIG gas sensor array can identify multiple gas species in the environment or exhaled breath.
The chemical inertness of poly(ethylene terephthalate) (PET) fabrics poses challenges in achieving superhydrophobic coatings with durable adhesion on their surfaces. Conventional surface modification methods such as alkali etching and plasma etching typically compromise the favorable mechanical properties of PET. In this study, polydopamine (PDA) was utilized to functionalize the PET fabric nondestructively by creating robust and reactive hydroxyl and amine groups on its surface, which were subsequently used as a binder of superhydrophobic modifiers such as fluorine-free octadecyltrichlorosilane (OTS). By utilizing PDA to provide reactive groups, OTS undergoes self-assembly through hydrolysis on the surface of the PET fabric without introducing any inorganic nanoparticles while simultaneously forming low surface energy, strong covalent bonds, and rough surfaces. This robust material system provides a novel strategy to design and prepare superhydrophobic PET fabrics that can withstand extreme conditions and maintain superb water repellency even after 1000 times of abrasion and 100 washing cycles. Additionally, the room-temperature self-assembly properties of OTS provide the modified PET fabrics with efficient and repeatable room-temperature self-healing capability. This entire process through an environmentally friendly two-step immersion method enables large-scale production of superhydrophobic PET fabrics with wide applications in sports shoes and clothing.
Skin-interfaced wearable sensors can continuously monitor various biophysical and biochemical signals for health monitoring and disease diagnostics. However, such devices are typically limited by unsatisfactory and unstable output performance of the power supplies under mechanical deformations and human movements. Furthermore, there is also a lack of a simple and cost-effective fabrication technique to fabricate and integrate varying materials in the device system. Herein, we report a fully integrated standalone stretchable biophysical sensing system by combining wearable biophysical sensors, triboelectric nanogenerator (TENG), microsupercapacitor arrays (MSCAs), power management circuits, and wireless transmission modules. All of the device components and interconnections based on the three-dimensional (3D) networked graphene/Co3O4 nanocomposites are fabricated via low-cost and scalable direct laser writing. The self-charging power units can efficiently harvest energy from body motion into a stable and adjustable voltage/current output to drive various biophysical sensors and wireless transmission modules for continuously capturing, processing, and wirelessly transmitting various signals in real-time. The novel material modification, device configuration, and system integration strategies provide a rapid and scalable route to the design and application of next-generation standalone stretchable sensing systems for health monitoring and human–machine interfaces.
We report a facile approach to fabricating stretchable superhydrophobic surfaces with different microstructures (arc-shaped or V-shaped air pockets) for multi-stage liquid droplet micro-reactors.
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