3D-Printable Carbon Nanotubes-Based Composite for Flexible Piezoresistive Sensors

The intersection between nanoscience and additive manufacturing technology has resulted in a new field of printable and flexible electronics. This interesting area of research tackles the challenges in the development of novel materials and fabrication techniques towards a wider range and improved design of flexible electronic devices. This work presents the fabrication of a cost-effective and facile flexible piezoresistive pressure sensor using a 3D-printable carbon nanotube-based nanocomposite. The carbon nanotubes used for the development of the material are multi-walled carbon nanotubes (MWCNT) dispersed in polydimethylsiloxane (PDMS) prepolymer. The sensor was fabricated using the direct ink writing (DIW) technique (also referred to as robocasting). The MWCNT-PDMS composite was directly printed onto the polydimethylsiloxane substrate. The sensor response was then examined based on the resistance change to the applied load. The sensor exhibited high sensitivity (6.3 Ω/kPa) over a wide range of applied pressure (up to 1132 kPa); the highest observed measurement range for MWCNT-PDMS composite in previous work was 40 kPa. The formulated MWCNT-PDMS composite was also printed into high-resolution 3-dimensional shapes which maintained their form even after heat treatment process. The possibility to use 3D printing in the fabrication of flexible sensors allows design freedom and flexibility, and structural complexity with wide applications in wearable or implantable electronics for sport, automotive and biomedical fields.

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MWCNT Devices Fabricated by Dielectrophoresis: Study of Their Electrical Behavior Related to Deposited Nanotube Amount for Gas Sensing Applications

Journal of Integrated Circuits and Systems ◽

10.29292/jics.v10i1.400 ◽

2015 ◽

Vol 10 (1) ◽

pp. 13-20

Author(s):

Elisabete Galeazzo ◽

Marcos C. Moraes ◽

Henrique E. M. Peres ◽

Michel O. S. Dantas ◽

Victor G. C. Lobo ◽

...

Keyword(s):

Carbon Nanotubes ◽

Gas Sensing ◽

High Sensitivity ◽

Cost Effective ◽

Adsorbed Water ◽

Fast Response ◽

Process Time ◽

Electrical Behavior ◽

Glass Substrates ◽

Sensing Applications

Intensive research has been focused on investigating new sensing materials, such as carbon nanotubes (CNT) because of their promising characteristics. However, there are challenges related to their application in commercial devices such as sensitivity, compatibility, and complexity of miniaturization, among others. We report the study of the electrical behavior of devices composed by multi-walled carbon nanotubes (MWCNT) deposited between aluminum electrodes on glass substrates by means of dielectrophoresis (DEP), which is a simple and cost-effective method. The devices were fabricated by varying the DEP process time. Remarkable changes in their electric resistance were noticed depending on the MWCNT quantities deposited. Other electrical properties of devices such as high sensitivity, fast response time and stability are also characterized in humid environment. A humidity sensing mechanism is proposed on the basis of charge transfer between adsorbed water molecules and the MWNTC surface or between water and the glass surface.

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Fabrication and Characterization of Polylactic Acid Electrospun Scaffolds Modified with Multi-Walled Carbon Nanotubes and Hydroxyapatite Nanoparticles

Biomimetics ◽

10.3390/biomimetics5030043 ◽

2020 ◽

Vol 5 (3) ◽

pp. 43

Author(s):

Athanasios Kotrotsos ◽

Prokopis Yiallouros ◽

Vassilis Kostopoulos

Keyword(s):

Mechanical Properties ◽

Carbon Nanotubes ◽

Polylactic Acid ◽

Physical And Mechanical Properties ◽

Polymeric Materials ◽

Cost Effective ◽

Electrospinning Process ◽

Wide Range ◽

Multi Walled Carbon Nanotubes ◽

Walled Carbon Nanotubes

The solution electrospinning process (SEP) is a cost-effective technique in which a wide range of polymeric materials can be electrospun. Electrospun materials can also be easily modified during the solution preparation process (prior SEP). Based on this, the aim of the current work is the fabrication and nanomodification of scaffolds using SEP, and the investigation of their porosity and physical and mechanical properties. In this study, polylactic acid (PLA) was selected for scaffold fabrication, and further modified with multi-walled carbon nanotubes (MWCNTs) and hydroxyapatite (HAP) nanoparticles. After fabrication, porosity calculation and physical and mechanical characterization for all scaffold types were conducted. More precisely, the morphology of the fibers (in terms of fiber diameter), the surface properties (in terms of contact angle) and the mechanical properties under the tensile mode of the fabricated scaffolds have been investigated and further compared against pristine PLA scaffolds (without nanofillers). Finally, the scaffold with the optimal properties was proposed as the candidate material for potential future cell culturing.

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Near cut-off wavelength operation of resonant waveguide grating biosensors

Scientific Reports ◽

10.1038/s41598-021-92327-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Balint Kovacs ◽

Fabio Aldo Kraft ◽

Zsolt Szabo ◽

Yousef Nazirizadeh ◽

Martina Gerken ◽

...

Keyword(s):

Numerical Simulations ◽

Optical Waveguides ◽

Refractive Index Change ◽

High Sensitivity ◽

Cost Effective ◽

Intensity Change ◽

Wavelength Shift ◽

Geometrical Parameters ◽

Guided Mode ◽

Wide Range

AbstractNumerical simulations and analytical calculations are performed to support the design of grating-coupled planar optical waveguides for biological sensing. Near cut-off and far from cut-off modes are investigated, and their characteristics and suitability for sensing are compared. The numerical simulations reveal the high sensitivity of the guided mode intensity near the cut-off wavelength for any refractive index change along the waveguide. Consequently, it is sufficient to monitor the intensity change of the near cut-off sensing mode, which leads to a simpler sensor design compared to those setups where the resonant wavelength shift of the guided mode is monitored with high precision. The operating wavelength and the sensitivity of the proposed device can be tuned by varying the geometrical parameters of the corrugated waveguide. These results may lead to the development of highly sensitive integrated sensors, which have a simple design and therefore are cost-effective for a wide range of applications. These numerical findings are supported with experimental results, where the cut-off sensing mode was identified.

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Lazy Wave Catenary Risers: Scaling Factors and Analytical Approximation of the Static Stress Range in the Touchdown Zone

Volume 4A: Pipeline and Riser Technology ◽

10.1115/omae2013-10273 ◽

2013 ◽

Author(s):

Lucile M. Quéau ◽

Mehrdad Kimiaei ◽

Mark F. Randolph

Keyword(s):

Oil And Gas ◽

Structural Response ◽

High Sensitivity ◽

Cost Effective ◽

Analytical Approximation ◽

Static Stress ◽

Analytical Determination ◽

Stress Range ◽

Dynamic Amplification Factor ◽

Wide Range

Offshore exploration and production of oil and gas continue to increase and move into ever deeper water. Steel catenary risers (SCRs) are one of the most cost effective type of risers in deep water. However, high sensitivity to vessel motions and hydrodynamic loading in the touchdown zone may limit the feasibility of SCR applications. In recent years, there has been a growing interest in the use of Lazy-wave catenary riser (LWR) due to their better fatigue performance in the touchdown zone through the damping effect of the buoyancy section. The design of LWR involves numerous parameters that lead to a wide range of configurations. Each of these configurations needs to be evaluated against several criteria with respect to geometry, strength and fatigue for instance. This paper presents how tools recently proposed to improve the design of standard SCRs can be extended to benefit LWR applications. The dimensionless groups governing the structural response of LWRs are established in the aim of easing sensitivity analysis to key input parameters for LWR design, assisting experiments and reducing the number of numerical simulations. Moreover, the DAF (dynamic amplification factor) approach for dynamic response which has previously been explored for SCRs could also be used to simplify design of LWRs. As DAF relies on the analytical determination of static response, this framework shows that analytical boundary layer solutions in conjunction with the use of a Winkler type soil model can efficiently and accurately predict the static stress range of LWRs observed in the TDZ.

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Wrinkle Structured Network of Silver-Coated Carbon Nanotubes for Wearable Sensors

Nanoscale Research Letters ◽

10.1186/s11671-019-3186-5 ◽

2019 ◽

Vol 14 (1) ◽

Cited By ~ 3

Author(s):

Zhongyun Yuan ◽

Zhen Pei ◽

Muhammad Shahbaz ◽

Qiang Zhang ◽

Kai Zhuo ◽

...

Keyword(s):

Carbon Nanotubes ◽

Dynamic Range ◽

Wearable Sensors ◽

Hand Movement ◽

Strain Range ◽

High Sensitivity ◽

High Dynamic Range ◽

Gauge Factor ◽

Resistance Change ◽

Multi Walled Carbon Nanotubes

AbstractSoft-strain-based sensors are being increasingly used across various fields, including wearable sensing, behavior monitoring, and electrophysiological diagnostics. However, throughout all applications, the function of these sensors is limited because of high sensitivity, high-dynamic range, and low-power consumption. In this paper, we focus on improving the sensitivity and strain range of the soft-strain-based sensor through structure, surface, and sensitive unit treatment. Nanosilver (Ag)-coated hydroxyl-functionalized multi-walled carbon nanotubes (OH-f MWCNTs) were explored for highly acute sensing. With stretching and depositing methods, Ag@OH-f MWCNTs and polydimethylsiloxane (PDMS) are fabricated into a wrinkled and sandwich structure for a soft-strain-based sensor. The electronic properties were characterized in that the gauge factor (GF) = ΔR/R0 was 412.32, and the strain range was 42.2%. Moreover, our soft-strain-based sensor exhibits features including flexibility, ultra-lightweight and a highly comfortable experience in terms of wearability. Finally, some physiological and behavioral features can be sampled by testing the exceptional resistance change, including the detection of breath, as well as facial and hand movement recognition. The experiment exhibits its superiority in terms of being highly sensitive and having an extensive range of sensing.

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An ultrasensitive and highly compressive piezoresistive sensor based on a biopolyol-reinforced polyurethane sponge coated with silver nanoparticles and carbon nanotubes/cellulose nanocrystals

Journal of Materials Chemistry C ◽

10.1039/d0tc04141f ◽

2020 ◽

Vol 8 (46) ◽

pp. 16603-16614

Author(s):

Qiming Yan ◽

Weidi Xie ◽

Meng Zhou ◽

Heqing Fu

Keyword(s):

Carbon Nanotubes ◽

Silver Nanoparticles ◽

Flexible Electronics ◽

Cellulose Nanocrystals ◽

Electronics Industry ◽

Piezoresistive Sensor ◽

Wide Range ◽

Polyurethane Sponge

A wearable, lightweight and wide-range detecting piezoresistive sensor is highly desired for the development of the flexible electronics industry.

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High Sensitivity Differential Giant Magnetoresistance (GMR) Based Sensor for Non-Contacting DC/AC Current Measurement

Sensors ◽

10.3390/s20010323 ◽

2020 ◽

Vol 20 (1) ◽

pp. 323 ◽

Cited By ~ 3

Author(s):

Mușuroi ◽

Oproiu ◽

Volmer ◽

Firastrau

Keyword(s):

Measurement System ◽

Giant Magnetoresistance ◽

High Sensitivity ◽

Measurement Range ◽

Current Measurement ◽

Local Fields ◽

Temperature Drift ◽

Wide Range ◽

Extended Operation ◽

High Flexibility

This paper presents the design and implementation of a high sensitivity giant magnetoresistance (GMR) based current sensor with a broad range of applications. The novelty of our approach consists in using a double differential measurement system, based on commercial GMR sensors, with an adjustable biasing system used to linearize the field response of the system. The work aims to act as a fully-operational proof of concept application, with an emphasis on the mode of operation and methods to improve the sensitivity and linearity of the measurement system. The implemented system has a broad current measurement range from as low as 75 mA in DC and 150 mA in AC up to 4 A by using a single setup. The sensor system is also very low power, consuming only 6.4 mW. Due to the way the sensors are polarized and positioned above the U-shaped conductive band through which the current to be measured is flowing, the differential setup offers a sensitivity of about between 0.0272 to 0.0307 V/A (signal from sensors with no amplifications), a high immunity to external magnetic fields, low hysteresis effects of 40 mA, and a temperature drift of the offset of about −2.59×10−4 A/°C. The system provides a high flexibility in designing applications where local fields with very low amplitudes must be detected. This setup can be redesigned for a wide range of applications, thus allowing further specific optimizations, which would provide an even greater accuracy and a significantly extended operation range.

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Using the Nonlinear Duffing Effect of Piezoelectric Micro-Oscillators for Wide-Range Pressure Sensing

Actuators ◽

10.3390/act10080172 ◽

2021 ◽

Vol 10 (8) ◽

pp. 172

Author(s):

Tobias Zengerle ◽

Michael Stopp ◽

Abdallah Ababneh ◽

Helmut Seidel

Keyword(s):

Duffing Oscillator ◽

Cost Effective ◽

Measurement Range ◽

Theoretical Background ◽

Pressure Measurements ◽

Softening Effect ◽

Coverage Area ◽

Novel Approach ◽

Wide Range ◽

Bending Modes

This paper investigates the resonant behaviour of silicon-based micro-oscillators with a length of 3600 µm, a width of 1800 µm and a thickness of 10 µm over a wide range of ambient gas (N2) pressures, extending over six orders of magnitude from 10−3 mbar to 900 mbar. The oscillators are actuated piezoelectrically by a thin-film aluminium-nitride (AlN) layer, with the cantilever coverage area being varied from 33% up to 100%. The central focus is on nonlinear Duffing effects, occurring at higher oscillation amplitudes. A theoretical background is provided. All relevant parameters describing a Duffing oscillator, such as stiffness parameters for each coverage size as well as for different bending modes and more complex modes, are extracted from the experimental data. The so-called 2nd roof-tile-shaped mode showed the highest stiffness value of −97.3∙107 m−2s−2. Thus, it was chosen as being optimal for extended range pressure measurements. Interestingly, both a spring softening effect and a spring hardening effect were observed in this mode, depending on the percentage of the AlN coverage area. The Duffing-effect-induced frequency shift was found to be optimal for obtaining the highest pressure sensitivity, while the size of the hysteresis loop is also a very useful parameter because of the possibility of eliminating the temperature influences and long-term drift effects of the resonance frequency. An reasonable application-specific compromise between the sensitivity and the measurement range can be selected by adjusting the excitation voltage, offering much flexibility. This novel approach turns out to be very promising for compact, cost-effective, wide-range pressure measurements in the vacuum range.

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Sensitivity Enhancement of Curvature Fiber Sensor Based on Polymer-Coated Capillary Hollow-Core Fiber

Sensors ◽

10.3390/s20133763 ◽

2020 ◽

Vol 20 (13) ◽

pp. 3763 ◽

Cited By ~ 2

Author(s):

Luis A. Herrera-Piad ◽

Iván Hernández-Romano ◽

Daniel A. May-Arrioja ◽

Vladimir P. Minkovich ◽

Miguel Torres-Cisneros

Keyword(s):

Fiber Optic ◽

High Sensitivity ◽

Single Mode ◽

Cost Effective ◽

Fiber Optic Sensor ◽

Hollow Core ◽

Sensing Applications ◽

Optic Sensor ◽

Wide Range ◽

Core Fiber

In this paper, we propose and experimentally demonstrate a simple technique to enhance the curvature sensitivity of a bending fiber optic sensor based on anti-resonant reflecting optical waveguide (ARROW) guidance. The sensing structure is assembled by splicing a segment of capillary hollow-core fiber (CHCF) between two single-mode fibers (SMF), and the device is set on a steel sheet for measuring different curvatures. Without any surface treatment, the ARROW sensor exhibits a curvature sensitivity of 1.6 dB/m−1 in a curvature range from 0 to 2.14 m−1. By carefully coating half of the CHCF length with polydimethylsiloxane (PDMS), the curvature sensitivity of the ARROW sensor is enhanced to −5.62 dB/m−1, as well as an increment in the curvature range (from 0 to 2.68 m−1). Moreover, the covered device exhibits a low-temperature sensitivity (0.038 dB/°C), meaning that temperature fluctuations do not compromise the bending fiber optic sensor operation. The ARROW sensor fabricated with this technique has high sensitivity and a wide range for curvature measurements, with the advantage that the technique is cost-effective and easy to implement. All these features make this technique appealing for real sensing applications, such as structural health monitoring.

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Silicon Carbide MEMS Capacitive Pressure Sensor for Harsh Environments

Volume 10: Micro- and Nano-Systems Engineering and Packaging ◽

10.1115/imece2013-64764 ◽

2013 ◽

Cited By ~ 3

Author(s):

Zhibang Chen ◽

Wei Du ◽

Feng Zhao

Keyword(s):

Silicon Carbide ◽

Pressure Sensor ◽

Large Scale ◽

Applied Pressure ◽

High Sensitivity ◽

Capacitive Pressure Sensor ◽

Wide Range ◽

Sensor Structure ◽

Nuclear Station ◽

Oil Gas

In this paper, we investigated a new capacitive pressure sensor structure on a silicon carbide (SiC) platform for high sensitivity and harsh environment operation capability. The superior material properties of SiC ensure robustness of the new sensor to withstand large-scale pressure at high temperature and in chemical/biological medium. The sensor structure consists of a circular SiC diaphragm suspended by four arms over a SiC substrate, with design to enable diaphragm to deflect nearly uniformly with applied pressure. This configuration results in improved sensing properties. With high sensitivity and operation capability in hostile environment, this new pressure sensor is promising for use in a wide range of applications such as automotive, nuclear station, aerospace, and oil/gas exploration, etc.

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