because the sensing information contains human behavior-related inputs to enable efficient communication, process control, and safety assurance. The technologies for behavior monitoring include cameras, [3] radar, [4] electromagnetic, [5] and capacitive sensing. Among the methods, capacitance sensing is unique in that both proximity and physical contact can be detected at a fraction of cost and power.Traditional capacitive sensors have been limited in flexibility, sensitivity, and proximity to serve HMI applications, including wearable devices. Recent progress has been made to incorporate nanostructures into the electrode design to offer flexible and stretchable functions. [6] A flexible capacitive sensor was fabricated by printing copper traces to form crossing junctions. [7] Silver-plated fiber electrodes in combination with silicone dielectric were fabricated for a motion-sensing band. [8] A flexible touch sensor was fabricated by printing a silver nano-ink onto a polyethylene terephthalate (PET) film. [9] The ionic liquid was enclosed into the silicone to create a flexible capacitive strain sensor. [10] On the other hand, various capacitive sensors were developed and commercialized as a touchscreen format for finger motion detection with contact. A conventional cylindrical capacitive sensor has a detection range proportional to the electrode diameter. For example, a 34 mm diameter electrode has a detection range of 40 mm. [11] Novel designs were made to improve the proximity range while reducing the electrode dimension. Selfcapacitive sensors were demonstrated to detect a human hand at 120 mm-distance but with a 100 mm-dimension. [12] Thermoplastic polyurethane-carbon nanotube (TPU-CNT) film sensors demonstrated a proximity detection range of 120 mm with a 60 mm dimension. [13] For capacitive sensors, larger capacitive electrodes offer higher sensitivity due to the larger characteristic length of an electric field. However, the large electrode reduces a spatial resolution, which is a challenge for delicate gesture recognition.This paper presents a capacitive sensor composed of a nanostructured electrode array. One capacitive electrode is composed of high aspect-ratio cellulose fibers embedded with multiwalled carbon nanotubes. The electrode array enlarges the capacitance with a reduced form factor. The capacitive sensing mechanism is analyzed by numerical analysis. The sensitivity of multiple Human-machine interface requires various sensors for communication, manufacturing and environmental control, and health and safety monitoring. Capacitive sensors have been used to detect touch, distance, geometry, electric property, and environmental parameters. However, highly sensitive proximity detection with a small form factor has always been a challenge. This paper presents a capacitive sensor composed of a nanostructured electrode array for contact and noncontact detection. In the sensor configuration, the nanostructured electrode is made of high aspect ratio cellulose fibers embedded with carbon nanotubes. The co...
Current point-of-care (POC) screening of Coronavirus disease 2019 (COVID-19) requires further improvements to achieve highly sensitive, rapid, and inexpensive detection. Here we describe an immunoresistive sensor on a polyethylene terephthalate (PET) film for simple, inexpensive, and highly sensitive COVID-19 screening. The sensor is composed of single-walled carbon nanotubes (SWCNTs) functionalized with monoclonal antibodies that bind to the spike protein of SARS-CoV-2. Silver electrodes are silkscreen-printed on SWCNTs to reduce contact resistance. We determine the SARS-CoV-2 status via the resistance ratio of control- and SARS-CoV-2 sensor electrodes. A combined measurement of two adjacent sensors enhances the sensitivity and specificity of the detection protocol. The lower limit of detection (LLD) of the SWCNT assay is 350 genome equivalents/mL. The developed SWCNT sensor shows 100% sensitivity and 90% specificity in clinical sample testing. Further, our device adds benefits of a small form factor, simple operation, low power requirement, and low assay cost. This highly sensitive film sensor will facilitate rapid COVID-19 screening and expedite the development of POC screening platforms.
Auxetic materials showing a negative Poisson’s ratio can offer unusual sensing capabilities due to drastic percolation changes. This study presents the capacitive response of wet-fractured carbon nanotube paper composites in exposure to humidity. A strained composite strip is fractured to produce numerous cantilevers consisting of cellulose fibers coated with carbon nanotubes. During stretching, the thin composite buckles in the out-of-plane direction, which causes auxetic behavior to generate the radially structured electrodes. The crossbar junctions forming among the fractured electrodes significantly increase capacitance and its response to humidity as a function of sensor widths. The molecular junctions switch electric characteristics between predominantly resistive- and capacitive elements. The resulting capacitive response is characterized for humidity sensing without the need for an additional absorption medium. The normalized capacitance change (ΔC/C) exhibits a sensitivity of 0.225 within the range of 40~80 % relative humidity. The novel auxetic behavior of a water-printed paper-based nanocomposite paves the way for inexpensive humidity and sweat sensors.
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.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.