Monitoring of personal healthcare requires multifunctional sensors that can sense both chemical and physical stimuli. One of the possible solutions is the fabrication of low-cost, disposable "one time use" functional nanomaterials based sensors that can sense multiple health parameters, and the sensor data can be wirelessly transmitted to the smartphone for further processing. This report is a first demonstration of the direct growth of NiSe 2 on cellulose paper by the solution processed hydrothermal method and its application for a smart personal healthcare monitoring system that includes a noninvasive periodontal diagnosis to monitor oral health by the use of human saliva, a breath analyzer for various breath-related diseases, and a gesture sensor for deaf, dumb, and aurally challenged patients to communicate with the world. The fabricated sensor can be customized for a specific sensing with a dedicated user-friendly Android application which can be accessed remotely by a smartphone. The detailed sensing mechanism of each sensor is explained in terms of charge transport and electron transfer mechanisms. Furthermore, the sensing performance does not fluctuate even after 500 bending cycles for both chemical and physical stimuli, thus enabling low-cost yet robust and reliable monitoring. Successful development of such a versatile platform finds wide applications in the field of smart healthcare, medical devices, and the internet of things.
Multifunctional sensors responding to different chemical stimuli fabricated using functional nanomaterials still remain a challenge because of the usage of the same sensor multiple times for different sensing applications and unreliable front-end processing of the sensing data. This challenge is intensified by the lack of suitable techniques for fabricating disposable sensors, which can be integrated into smartphones with a dedicated application developed for each sensing application. A novel MoS/CuS hybrid grown on disposable cellulose paper by the hydrothermal method is reported for its utilization in sensing humidity, temperature, breath, and ethanol adulteration, wherein the data can be wirelessly transmitted to a smartphone with the dedicated application module for each sensing application. The sensor can be utilized for a particular sensing application and then can be disposed, avoiding the need for utilizing the same sensor for different sensing applications, thereby increasing the accuracy of the sensing data. The sensing mechanism of the fabricated sensor is explained for each stimulus in terms of change in the transport properties of the MoS/CuS hybrid. The development of such unique hybrid materials for wireless disposable multifunctional sensors is a great step ahead in flexible and wearable electronics having potential applications in medical, security, Internet of things, etc.
Methyl jasmonate (MeJa), a vital phytohormone plays a crucial role in plant growth and defense mechanisms to protect plants against biotic as well as abiotic stresses. Therefore, easy and accurate detection of MeJa in a user-friendly, comprehensive manner by farmers is of utmost significance in agriculture. This work reports a first of its kind ultra-low-cost pyrite FeS 2 based smart sensor on flexible paper substrate for determination of MeJa with a detection limit of 0.2 mM, excellent selectivity, reproducibility, and high sensitivity. Firstly, the electrochemical sensor based on pyrite FeS 2 exhibited a sensitivity of 412.2 μA.mM −1 .cm −2 (R 2 =0.971) in the physiologically relevant range of 0.25-1.5 mM and 230.4 μA.mM −1 .cm −2 (R 2 =0.990) in the region of 1.5-4.5 mM of MeJa. This significant enhancement in the analytical performances of the FeS 2 sensor can be ascribed to the high conductivity of the pyrite FeS 2 , large surface area resulting from its microspheres like morphology comprising of interwoven vertically grown nano-sheets and the presence of defects in FeS 2 structure. Further, wireless monitoring of MeJa was achieved by direct growth of pyrite FeS 2 on cellulose paper by hydrothermal method and its integration with the microcontroller, from where the data collected was transported to a smartphone via Bluetooth, thus facilitating remote sensing. The pyrite FeS 2 based disposable, chemi-resistive sensor displayed limit of detection of 0.68 mM and excellent sensitivity of 12.24±1.4% mM −1 (R 2 =0.96) in the range of 1-2.5 mM of MeJa. The development of such lowcost nano-material based disposable sensor is a huge step ahead in the fabrication of affordable, nextgeneration lab-on-chip devices for analytical applications.
Flexible, wearable, functional sensors that can quantify electrical signals generated by human activities are of great importance in personal healthcare monitoring. However, the high fabrication cost of these sensors along with the unreliable front-end processing of data restricts their widespread usage. In this report, we demonstrate MoS 2 growth on Al foil which was further integrated onto eraser substrate to develop smart, low-cost motion sensors (pedometer and gesture communication) and a breath sensor by measuring physiological parameters such as strain, touch and hydration levels of lungs, respectively. The data generated are wirelessly transmitted to the smartphone via Bluetooth and analyzed using dedicated Android applications for individual sensing displays. For the pedometer, the fabricated sensor was integrated onto the knee which could then calculate the steps taken, distance covered, speed and approximate number of calories burned by the individual. Gesture communication helps deaf/dumb/paralyzed individuals to communicate with the external environment using finger movements. Breath sensing allows for the early detection of lung diseases by monitoring the hydration levels of the lungs. Furthermore, the piezotronic effect of MoS 2 on breath sensing was systematically studied, and a 56.8% increase in the response was observed under a 16% strain. The sensing mechanism for each stimulus is explained via modulation in the charge transport properties for each stimulus. The sensor exhibited excellent durability where the device performance was found to be stable even after 500 continuous bending cycles. The successful demonstration of such low-cost functional wireless personal healthcare monitoring systems for Internet of Things applications is a major step forward in flexible and wearable electronics.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.