10 research outputs found
Disposable sensors in diagnostics, food and environmental monitoring
Disposable sensors are lowâcost and easyâtoâuse sensing devices intended for shortâterm or rapid singleâpoint measurements. The growing demand for fast, accessible, and reliable information in a vastly connected world makes disposable sensors increasingly important. The areas of application for such devices are numerous, ranging from pharmaceutical, agricultural, environmental, forensic, and food sciences to wearables and clinical diagnostics, especially in resourceâlimited settings. The capabilities of disposable sensors can extend beyond measuring traditional physical quantities (for example, temperature or pressure); they can provide critical chemical and biological information (chemoâ and biosensors) that can be digitized and made available to users and centralized/decentralized facilities for data storage, remotely. These features could pave the way for new classes of lowâcost systems for health, food, and environmental monitoring that can democratize sensing across the globe. Here, a brief insight into the materials and basics of sensors (methods of transduction, molecular recognition, and amplification) is provided followed by a comprehensive and critical overview of the disposable sensors currently used for medical diagnostics, food, and environmental analysis. Finally, views on how the field of disposable sensing devices will continue its evolution are discussed, including the future trends, challenges, and opportunities
Enhanced electrical properties and large electrocaloric effect in lead-free Ba0.8Ca0.2ZrxTi1âxO3 (xâ=â0 and 0.02) ceramics
The effects of 2% Zr introduction in Ba0.8Ca0.2TiO3 (BCT) system on its electrical and electrocaloric properties was investigated. BCT and Ba0.8Ca0.2Zr0.02Ti0.98O3 (BCZT) ceramics synthesized by solid-state processing were crystallized in a pure perovskite phase with a group space P4mm. After Zr insertion, the enhanced dielectric constant was obtained around the Curie temperature (Tc) in BCZT ceramic (Δrâ=â6330 at Tcâ=â388 K) compared to BCT ceramic (Δrâ=â5080 at Tcâ=â388.6 K). Moreover, the large-signal piezoelectric coefficient (dâ33) was improved from 270 to 310 pm/V in BCT and BCZT ceramics, respectively, under a moderate electric field of 25 kV/cm. The electrocaloric effect was determined via indirect and direct methods. In the indirect approach, the electrocaloric temperature change (ÎT) was calculated via Maxwell relation, and the measured ferroelectric polarization P (E, T) extracted from the PâE curves recorded at 24 kV/cm. The maximum values of ÎTâ=â0.68 K and the electrocaloric responsivity ζâ=â0.283 K mm/kV obtained at 385 K in BCZT ceramic were found to be higher than those observed in BCT ceramic (ÎTâ=â0.37 K and ζâ=â0.154 K mm/kV at 387 K). In the direct approach, ÎT was measured utilizing a modified high-resolution calorimeter at 14 kV/cm. As the direct method is more sensitive to the latent heat, it provided larger values for smaller applied field, i.e., ÎTâ=â0.474 and 0.668 K for BCT and BCZT ceramics, respectively. A significant ζ of 0.477 K mm/kV was obtained in BCZT at 385 K and 14 kV/cm that matches the values found in lead-based materials. These results suggest that BCZT lead-free ceramics could have an excellent potential to be used in solid-state refrigeration applications