Printable Carbon Nanotube-Liquid Elastomer-Based Multifunctional Adhesive Sensors for Monitoring Physiological Parameters

Abstract

Developing a printed elastomeric wearable sensor with good conformity and proper adhesion to skin, coupled with the capability of monitoring various physiological parameters, is very crucial for the development of point-of-care sensing devices with high precision and sensitivity. While there have been previous reports on the fabrication of elastomeric multifunctional sensors, research on the printable elastomeric multifunctional adhesive sensor is not very well explored. Herein, we report the development of a stencil printable multifunctional adhesive sensor fabricated in a solvent-free condition, which demonstrated the capability of having good contact with skin and its ability to function as a temperature and strain sensor. Functionalized liquid isoprene rubber was selected as the matrix while carboxylated multiwalled carbon nanotubes (c-CNTs) were used as the nanofiller. The selection of the above model compounds facilitated the printability and also helped the same composition to demonstrate stretchability and adhesiveness. A realistic three-dimensional microstructure (representative volume element model) was generated through a computational framework for the current c-CNT-liquid elastomer. Further computational simulations were performed to test and validate the correlation between electrical responses to that of experimental studies. Various physiological parameters like motion sensing, pulse, respiratory rate, and phonetics detection were detected by leveraging the electrically resistive nature of the sensor. This development route can be extended toward developing different innovative adhesives for point-of-care sensing applications.

Printable Graphene-Sustainable Elastomer-Based Cross Talk Free Sensor for Point of Care Diagnostics

“…Moreover, conductivity showed an exponential increase as graphene concentrations increased. Power law that governs the phenomena of exponential increase can be quantified using the following equation: (1) where φ, φ c, , and n are the volume fraction of filler, percolation volume fractions, and critical exponent. The conversion of conductivity and volume fraction data to log scale shows a linear trend after percolation, signifying that data follows the power-law (depicted in the log−log fitting curves between conductivity and volume fraction, Figure 2c).…”

“…Millennials across the globe prefer electronic devices that are thin, compact, and flexible in terms of their form factor, largely classified as flexible electronics. A broad-spectrum application to which flexible electronics can cater ranges from the healthcare sector and energy to automobiles. , As per the market predictions, the total revenue of flexible electronics in the healthcare sector will exceed 8.3 billion USD by 2030. − Additionally, the use of such flexible electronics in the healthcare segment in conjunction with the Internet of Things (IoT) is stiffly rising. This is due to their unique ability to sense external stimuli like pressure, temperature, etc. − To establish a conformable contact to the human skin, polymers and their composites are leveraged for making the sensors that are otherwise difficult to achieve using a traditional sensor based on ceramics and metals.…”

“…A broad-spectrum application to which flexible electronics can cater ranges from the healthcare sector and energy to automobiles. 1,2 As per the market predictions, the total revenue of flexible electronics in the healthcare sector will exceed 8.3 billion USD by 2030. 3−5 Additionally, the use of such flexible electronics in the healthcare segment in conjunction with the Internet of Things (IoT) is stiffly rising.…”

Cross-Talk Signal Free Recyclable Thermoplastic Polyurethane/Graphene-Based Strain and Pressure Sensor for Monitoring Human Motions

“…This causes difficulty to predict whether the signal so generated originated from which external impulse and is commonly referred to as the cross-talk of the signals of the sensors. In terms of the filler, graphene, − carbon nanotubes, ,− silver nanowires, − carbon black, − and hybrid nanostructures − are commonly used as the functional sensing component. However, among the different classes of the fillers that are being used for sensing, graphene has gained a great deal of attention as a potentially useful candidate for the development of new-generation electronic devices. , Under strain, the graphene alters its electronic structure, which in turn will cause a significant shift in the resistance of the material. ,, This ability of graphene along with the superior mechanical and electrical properties, carrier mobility, and ultra-translucency paved the way for graphene to be used in high-sensitivity strain sensors. − …”

Synthesis of Polyetheramine-Grafted Epoxidized Natural Rubber and Its Role in Humidity Adhesive Sensors

“…Multiple advantages of adhesive technology over mechanical fixation and welding technology have resulted in the exponential growth of research in the said domain. As a result, adhesive technology is paving its way to advanced applications from aerospace, automotive, and electronics to biomedical applications. − As far as adhesive technology is concerned, briefly, adhesives can be defined as a material that allows two similar or different substances to stick together and resist separation. Its interfacial bond strength results from chemical and electrostatic bonding and secondary forces such as hydrogen bonding, van der Waals, and so forth .…”