Wearable devices provide an alternative pathway to clinical diagnostics by exploiting various physical, chemical and biological sensors to mine physiological (biophysical and/or biochemical) information in real time (preferably, continuously) and in a non-invasive or minimally invasive manner. These sensors can be worn in the form of glasses, jewellery, face masks, wristwatches, fitness bands, tattoo-like devices, bandages or other patches, and textiles. Wearables such as smartwatches have already proved their capability for the early detection and monitoring of the progression and treatment of various diseases, such as COVID-19 and Parkinson disease, through biophysical signals. Next-generation wearable sensors that enable the multimodal and/or multiplexed measurement of physical parameters and biochemical markers in real time and continuously could be a transformative technology for diagnostics, allowing for high-resolution and time-resolved historical recording of the health status of an individual. In this Review, we examine the building blocks of such wearable sensors, including the substrate materials, sensing mechanisms, power modules and decision-making units, by reflecting on the recent developments in the materials, engineering and data science of these components. Finally, we synthesize current trends in the field to provide predictions for the future trajectory of wearable sensors.

Advanced printing and deposition methodologies are revolutionising the way biological molecules are deposited and leading to changes in the mass production of biosensors and biodevices. This revolution is being delivered principally through adaptations of printing technologies to device fabrication, increasing throughputs, decreasing feature sizes and driving production costs downwards. This review looks at several of the most relevant deposition and patterning methodologies that are emerging, either for their high production yield, their ability to reach micro- and nano-dimensions, or both. We look at inkjet, screen, microcontact, gravure and flexographic printing as well as lithographies such as scanning probe, photo- and e-beam lithographies and laser printing. We also take a look at the emerging technique of plasma modification and assess the usefulness of these for the deposition of biomolecules and other materials associated with biodevice fabrication.

No abstract

Readily deployable, low-cost point-of-care medical devices such as lateral flow assays (LFAs), microfluidic paper-based analytical devices (μPADs), and microfluidic thread-based analytical devices (μTADs) are urgently needed in resource-poor settings. Governed by the ASSURED criteria (affordable, sensitive, specific, user-friendly, rapid and robust, equipment-free, and deliverability) set by the World Health Organization, these reliable platforms can screen a myriad of chemical and biological analytes including viruses, bacteria, proteins, electrolytes, and narcotics. The Ebola epidemic in 2014 and the ongoing pandemic of SARS-CoV-2 have exemplified the ever-increasing importance of timely diagnostics to limit the spread of diseases. This review provides a comprehensive survey of LFAs, μPADs, and μTADs that can be deployed in resource-limited settings. The subsequent commercialization of these technologies will benefit the public health, especially in areas where access to healthcare is limited.

No abstract

No abstract

An electrochemical approach to directly measure the dynamic process of H2O2 release from cultures of Arabidopsis thaliana cells is reported. This approach is based on H2O2 oxidation on a Pt electrode in conjunction with continuous measurement of sample pH. For [H2O2] <1 mM, calibration plots were linear and the amperometric response of the electrode was maximum at pH 6. At higher concentrations ([H2O2] >1 mM), the amperometric response can be described by Michaelian-type kinetics and a mathematical expression relating current intensity and pH was obtained to quantitatively determine H2O2 concentration. At pH 5.5, the detection limit of the sensor was 3.1 mM (S/N = 3), with a response sensitivity of 0.16 AM -1 cm -2 and reproducibility was within 6.1% in the range 1-5 ¥ 10 -3 M (n = 5). Cell suspensions under normal physiological conditions had a pH between 5.5-5.7 and H2O2 concentrations in the range 7.0-20.5 mM (n = 5). The addition of exogenous H2O2, as well as other potential stress stimuli, was made to the cells and the change in H2O2 concentration was monitored. This real-time quantitative H2O2 analysis is a potential marker for the evaluation of oxidative stress in plant cell cultures.

The modification of silver screen‐printed electrodes with a dodecyl benzenesulfonic acid and KCl solution was performed by inkjet printing. Scanning Electron Microscopy was performed to characterize the electrode surfaces. Electrochemical reduction of H2O2 was studied and compared to electrodes modified by dip‐coating. Analytical parameters of the all‐printed electrode such as LOD, sensitivity and inter‐electrode reproducibility were calculated (5.8×10−6 M, 4.9×10−2 AM−1 cm−2 and approx. 10 %) and contrasted with other data in the literature for the measurement of H2O2. Ink jet printing led to reductions in required surface modification times and improved signal to background levels and reproducibility.