In this manner, sensor technologies have garnered great attention in various fields, including biomedicine, [2][3][4][5] environmental monitoring, [6][7][8][9] smart devices, [10] wearable devices, [11] automobile manufacturing [12] since the semiconductor materials and circuits have been developed. In particular, biosensors are powerful and innovative analytical tools that incorporate biological receptors to recognize biological analytes through either physical or chemical transducers. Primarily, bio-receptors are responsible for identifying and capturing target analytes, and the transducer basically translates biological and chemical information into the detectable signals, which are eventually converted into the concentration of the analyte. [13,14] Considering gold standard methods, such as enzyme-linked immunosorbent assay (ELISA) [15] and polymerase chain reaction (PCR)-based strategies, [16] biosensors mostly hold crucial features, such as i) short assay time, [17] ii) affordable tools and reagents, [18] iii) portability, [19] and iv) facile use and minimum user interpretation. [20] Nowadays, the applications of biosensors have been leveraged by the advancements of portable and miniaturized platforms. In particular, over the past years, wearable health monitoring devices have notable impact on continuous and real-time monitoring of health parameters, thereby accelerating the deployment of biosensing strategies to daily lives. Besides, non-invasive and ease-of-collecting information supports the benefits of the wearable systems for enhancing the awareness of individuals and communities. [21][22][23] The special features of the mechanically flexible and stable wearable sensors include remarkable means, such as portability, comfortability, light-weight, non-invasive, and reliable performance. To put it simply, wearable sensors are readily attached to skin or organ surfaces through an adhesive tape [24] or microneedles, [25] and because of such easy integrations, several researchers have focused on developing wearable sensors for real-time health monitoring. A wearable sensor is basically composed of some vital elements, including a flexible base material attached to the skin or an organ, a signal transfer electrode, and a biorecognition element. Recently, researchers have concentrated on creating integrated sensors that are able to measure various parameters simultaneously, such as pressure, temperature,The healthcare system has a drastic paradigm shift from centralized care to home-based and self-monitoring strategies; aiming to reach more individuals, minimize workload in hospitals, and reduce healthcare-associated expenses. Particularly, wearable technologies are garnering considerable interest by tracking physiological parameters through motion and activities, and monitoring biochemical markers from sweat, saliva, and tears. Through their integrations with sensors, microfluidics, and wireless communication systems, they allow physicians, family members, or individuals to monitor multiple parameters withou...

After the first case has appeared in China, the COVID-19 pandemic continues to pose an omnipresent threat to global health, affecting more than 70 million patients and leading to around 1.6 million deaths. To implement rapid and effective clinical management, early diagnosis is the mainstay. Today, real-time reverse transcriptase (RT)-PCR test is the major diagnostic practice as a gold standard method for accurate diagnosis of this disease. On the other side, serological assays are easy to be implemented for the disease screening. Considering the limitations of today's tests including lengthy assay time, cost, the need for skilled personnel, and specialized infrastructure, both strategies, however, have impediments to be applied to the resource-scarce settings. Therefore, there is an urgent need to democratize all these practices to be applicable across the globe, specifically to the locations comprising of very limited infrastructure. In this regard, sensor systems have been utilized in clinical diagnostics largely, holding great potential to have pivotal roles as an alternative or complementary options to these current tests, providing crucial fashions such as being suitable for point-of-care settings, cost-effective, and having short turnover time. In particular, the integration of smart materials into sensor technologies leverages their analytical performances, including sensitivity, linear dynamic range, and specificity. Herein, we comprehensively review major smart materials such as nanomaterials, photosensitive materials, electrically sensitive materials, their integration with sensor platforms, and applications as wearable tools within the scope of the COVID-19 diagnosis.

Skin is the largest epithelial surface of the human body, with a surface area of 2 m2 for the average adult human. Being an external organ, it is susceptible to more than 3000 potential skin diseases, including injury, inflammation, microbial and viral infections, and skin cancer. Due to its nature, it offers a large accessible site for administrating several medications against these diseases. The dermal and transdermal delivery of such medications are often ensured by utilizing dermal/transdermal patches or microneedles made of biocompatible and biodegradable materials. These tools provide controlled delivery of drugs to the site of action in a rapid and therapeutically effective manner with enhanced diffusivity and minimal side effects. Regrettably, they are usually fabricated using synthetic materials with possible harmful environmental effects. Manufacturing such tools using green synthesis routes and raw materials is hence essential for both ecological and economic sustainability. In this review, natural materials including chitosan/chitin, alginate, keratin, gelatin, cellulose, hyaluronic acid, pectin, and collagen utilized in designing ecofriendly patches will be explored. Their implementation in wound healing, skin cancer, inflammations, and infections will be discussed, and the significance of these studies will be evaluated with future perspectives.