Embedded 3D Printing of Highly Flexible Nanocomposites With Piezoresistive Sensing Capabilities

2020 ◽  
Author(s):  
Blake Herren ◽  
Mrinal C. Saha ◽  
M. Cengiz Altan ◽  
Yingtao Liu
Keyword(s):  
3D Printing ◽  
Human Skin ◽  
Strain Sensor ◽  
Strain Range ◽  
High Sensitivity ◽  
Curing Temperature ◽  
Gauge Factor ◽  
Strain Sensing ◽  
Sensing Applications ◽  
Human Joints

Abstract In recent years, highly flexible nanocomposite sensors have been developed for the detection of a variety of human body movements. To precisely detect the bending motions of human joints, the sensors must be able to conform well with the human skin and produce signals that effectively describe the amount of deformation applied to the material during bending. In this paper, a carbon nanotube-based piezoresistive strain sensor is developed via the direct ink writing based embedded 3D printing method. The optimum weight concentration range of carbon nanotubes in the nanocomposite inks, appropriate for embedded 3D printing, is identified. Samples with complex 2D and 3D geometries are printed to demonstrate the manufacturing capabilities of the embedded printing process. The sensitivity of the piezoresistive strain sensor is optimized by determining the ideal nanofiller concentration, curing temperature, and nozzle size to produce the highest gauge factor in a wide strain range. The piezoresistive and mechanical properties of the optimized sensors are fully characterized to verify the suitability for skin-attachable strain sensing applications. The developed sensors have a wide sensing range, high sensitivity, and minimal strain rate dependence. In addition, their low elasticity and high biocompatibility allow them to be comfortably bonded on the human skin.

Optimization of 3D Printed Elastomeric Nanocomposites for Flexible Strain Sensing Applications

2019 ◽  
Author(s):  
Mohammad Abshirini ◽  
Mohammad Charara ◽  
Mrinal C. Saha ◽  
M. Cengiz Altan ◽  
Yingtao Liu
Keyword(s):  
3D Printing ◽  
Strain Sensor ◽  
Sensitive Strain ◽  
Curing Temperature ◽  
Gauge Factor ◽  
Strain Sensing ◽  
Sensing Applications ◽  
Wide Range ◽  
Load Rate ◽  
3D Printed

Abstract Flexible and sensitive strain sensors can be utilized as wearable sensors and electronic devices in a wide range of applications, such as personal health monitoring, sports performance, and electronic skin. This paper presents the fabrication of a highly flexible and sensitive strain sensor by 3D printing an electrically conductive polydimethylsiloxane (PDMS)/multi-wall carbon nanotube (MWNT) nanocomposite on a PDMS substrate. To maximize the sensor’s gauge factor, the effects of MWNT concentration on the strain sensing function in nanocomposites are evaluated. Critical 3D printing and curing parameters, such as 3D printing nozzle diameter and nanocomposites curing temperature, are explored to achieve the highest piezoresistive response, showing that utilizing a smaller deposition nozzle size and higher curing temperature can result in a higher gauge factor. The optimized 3D printed nanocomposite sensor’s sensitivity is characterized under cyclic tensile loads at different maximum strains and loading rates. A linear piezoresistive response is observed up to 70% strain with an average gauge factor of 12, pointing to the sensor’s potential as a flexible strain sensor. In addition, the sensing function is almost independent of the applied load rate. The fabricated sensors are attached to a glove and used as a wearable sensor by detecting human finger and wrist motion. The results indicate that this 3D printed functional nanocomposite shows promise in a broad range of applications, including wearable and skin mounted sensors.

Direct Printing of a Flexible Strain Sensor for Distributed Monitoring of Deformation in Inflatable Structures

2019 ◽  
Author(s):  
Mohammed Al-Rubaiai ◽  
Ryohei Tsuruta ◽  
Taewoo Nam ◽  
Umesh Gandhi ◽  
Xiaobo Tan
Keyword(s):  
3D Printing ◽  
Structural Changes ◽  
Strain Sensor ◽  
Strain Range ◽  
Gauge Factor ◽  
Distributed Monitoring ◽  
Inflatable Structures ◽  
Resistance Change ◽  
Flexible Strain Sensor ◽  
Conductive Paint

Abstract Inflatable structures provide significant volume and weight savings for future space and soft robotic applications. Structural health monitoring (SHM) of these structures is essential to ensuring safe operation, providing early warnings of damage, and measuring structural changes over time. In this paper, we propose the design of a single flexible strain sensor for distributed monitoring of an inflatable tube, in particular, the detection and localization of a kink should that occur. Several commercially available conductive materials, including 3D-printing filaments, conductive paint, and conductive fabrics are explored for their strain-sensing performance, where the resistance change under uniaxial tension is measured, and the corresponding gauge factor (GF) is characterized. Flexible strain sensors are then fabricated and integrated with an inflatable structure fabric using screen-printing or 3D-printing techniques, depending on the nature of the raw conductive material. Among the tested materials, the conductive paint shows the highest stability, with GF of 15 and working strain range of 2.28%. Finally, the geometry of the sensor is designed to enable distributed monitoring of an inflatable tube. In particular, for a given deformation magnitude, the sensor output shows a monotonic relationship with the location where the deformation is applied, thus enabling the monitoring of the entire tube with a single sensor.

Characterization of MWCNTs-polystyrene nanocomposite based strain sensor

2020 ◽  
pp. 095440892096630
Author(s):  
Tarun Singla ◽  
Amrinder Pal Singh ◽  
Suresh Kumar ◽  
Gagandeep Singh ◽  
Navin Kumar
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Response ◽  
Composite Films ◽  
Tensile Load ◽  
High Sensitivity ◽  
Gauge Factor ◽  
Strain Sensing ◽  
Nano Composite ◽  
Microscopy Technique ◽  
Sensing Applications

The usage of nano phase materials for strain sensing applications has attracted attention due to their unique electromechanical properties. The nanocomposite as piezo-resistive films provides an alternative for the realization of strain sensors with high sensitivity than the conventional sensors based on metal and semiconductor strain gauges. In this work, polymer based nano-composite with carbon nanotubes as filler were developed. The multi-walled carbon nanotubes/polystyrene (MWCNTs/PS) nano-composite films were prepared with different wt.% of CNTs using solution mixing method. Field emission scanning electron microscopy technique was carried out to investigate the morphology and dispersion of CNTs in the nano-composite sample. Fourier transform infrared spectroscopy technique was employed to characterize the bonds present in the prepared nano-composite. The electrical response of the composite films was recorded in the form of current-voltage (I-V) characteristics using source meter. The electromechanical response of the nano-composite films with different wt.% of filler CNTs was recorded by applying uni-axial tensile load. The electromechanical responses were then analyzed to obtain gauge factor for the strain sensitivity. The highest gauge factor of 133 was recorded during tensile testing of the nano-composite with 3 wt.% of CNTs fillers.

scholarly journals Graphene as a Piezoresistive Material in Strain Sensing Applications

Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 119
Author(s):  
Farid Sayar Irani ◽  
Ali Hosseinpour Shafaghi ◽  
Melih Can Tasdelen ◽  
Tugce Delipinar ◽  
Ceyda Elcin Kaya ◽  
...  
Keyword(s):  
Mechanical Strain ◽  
Evolutionary Process ◽  
Strain Range ◽  
Device Fabrication ◽  
Strain Sensors ◽  
Gauge Factor ◽  
Strain Sensing ◽  
Characterization Methods ◽  
Accuracy Measurement ◽  
Sensing Applications

High accuracy measurement of mechanical strain is critical and broadly practiced in several application areas including structural health monitoring, industrial process control, manufacturing, avionics and the automotive industry, to name a few. Strain sensors, otherwise known as strain gauges, are fueled by various nanomaterials, among which graphene has attracted great interest in recent years, due to its unique electro-mechanical characteristics. Graphene shows not only exceptional physical properties but also has remarkable mechanical properties, such as piezoresistivity, which makes it a perfect candidate for strain sensing applications. In the present review, we provide an in-depth overview of the latest studies focusing on graphene and its strain sensing mechanism along with various applications. We start by providing a description of the fundamental properties, synthesis techniques and characterization methods of graphene, and then build forward to the discussion of numerous types of graphene-based strain sensors with side-by-side tabular comparison in terms of figures-of-merit, including strain range and sensitivity, otherwise referred to as the gauge factor. We demonstrate the material synthesis, device fabrication and integration challenges for researchers to achieve both wide strain range and high sensitivity in graphene-based strain sensors. Last of all, several applications of graphene-based strain sensors for different purposes are described. All in all, the evolutionary process of graphene-based strain sensors in recent years, as well as the upcoming challenges and future directions for emerging studies are highlighted.

scholarly journals High-Performance Wearable Strain Sensor Based on MXene@Cotton Fabric with Network Structure

2021 ◽  
Author(s):  
Lu Liu ◽  
Libo Wang ◽  
Xuqing Liu ◽  
Wenfeng Yuan ◽  
Mengmeng Yuan ◽  
...  
Keyword(s):  
Cotton Fabric ◽  
High Performance ◽  
Mechanical Performance ◽  
Active Material ◽  
Large Body ◽  
Strain Sensor ◽  
Strain Range ◽  
High Sensitivity ◽  
Strain Sensors ◽  
Gauge Factor

Abstract Although 2D nanomaterials such as MXene Ti3C2Tx have been used in flexible electronic devices for their unique properties such as high conductivity, excellent mechanical performance, flexibility, and good hydrophilicity, less research has focused on of MXene-based cotton fabric strain sensors. Moreover, fabrication of wearable strain sensors with a low cost, high sensitivity, good biocompatibility, and broad sensing range is still a challenge. In this work, a high-performance wearable strain sensor composed of 2D MXene d-Ti3C2Tx nanomaterials and cotton fabric is reported. As the active material in the sensor, MXene d-Ti3C2Tx exhibited an excellent conductivity and hydrophilicity and adhered well to the fabric fibers by electrostatic adsorption. Due to the unique structure of the fabric substrate and the properties of MXene sheets, the fabricated pressure sensor achieved a high sensitivity. The gauge factor of the MXene@cotton fabric strain sensor reached up to 4.11 within the strain range of 15 %. Meanwhile, the sensor possessed high durability (>500 cycles) and a low strain detection limit of 0.3%. Finally, the encapsulated strain sensor was used to detect subtle or large body movements and exhibited a rapid response. This study shows that the MXene@cotton fabric strain sensor reported here have great potential for use in flexible, comfortable, and wearable devices for health monitoring and motion detection.

scholarly journals Graphene/PVA buckypaper for strain sensing application

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ahsan Mehmood ◽  
N. M. Mubarak ◽  
Mohammad Khalid ◽  
Priyanka Jagadish ◽  
Rashmi Walvekar ◽  
...  
Keyword(s):  
Testing Machine ◽  
Strain Range ◽  
Industrial Applications ◽  
Human Motion ◽  
Gauge Factor ◽  
Strain Sensing ◽  
Tensile Testing Machine ◽  
Sensor Applications ◽  
Human Motion Detection ◽  
Sensing Applications

AbstractStrain sensors in the form of buckypaper (BP) infiltrated with various polymers are considered a viable option for strain sensor applications such as structural health monitoring and human motion detection. Graphene has outstanding properties in terms of strength, heat and current conduction, optics, and many more. However, graphene in the form of BP has not been considered earlier for strain sensing applications. In this work, graphene-based BP infiltrated with polyvinyl alcohol (PVA) was synthesized by vacuum filtration technique and polymer intercalation. First, Graphene oxide (GO) was prepared via treatment with sulphuric acid and nitric acid. Whereas, to obtain high-quality BP, GO was sonicated in ethanol for 20 min with sonication intensity of 60%. FTIR studies confirmed the oxygenated groups on the surface of GO while the dispersion characteristics were validated using zeta potential analysis. The nanocomposite was synthesized by varying BP and PVA concentrations. Mechanical and electrical properties were measured using a computerized tensile testing machine, two probe method, and hall effect, respectively. The electrical conducting properties of the nanocomposites decreased with increasing PVA content; likewise, electron mobility also decreased while electrical resistance increased. The optimization study reports the highest mechanical properties such as tensile strength, Young’s Modulus, and elongation at break of 200.55 MPa, 6.59 GPa, and 6.79%, respectively. Finally, electrochemical testing in a strain range of ε ~ 4% also testifies superior strain sensing properties of 60 wt% graphene BP/PVA with a demonstration of repeatability, accuracy, and preciseness for five loading and unloading cycles with a gauge factor of 1.33. Thus, results prove the usefulness of the nanocomposite for commercial and industrial applications.

scholarly journals Nano-Cracked Strain Sensor with High Sensitivity and Linearity by Controlling the Crack Arrangement

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2834 ◽  
Author(s):  
Hyunsuk Jung ◽  
Chan Park ◽  
Hyunwoo Lee ◽  
Seonguk Hong ◽  
Hyonguk Kim ◽  
...  
Keyword(s):  
Pulse Wave ◽  
Wearable Sensors ◽  
Strain Sensor ◽  
Strain Range ◽  
High Sensitivity ◽  
Strain Sensors ◽  
Gauge Factor ◽  
Micro Deformation ◽  
Sensing Performance ◽  
Limited Sensitivity

Studies on wearable sensors that monitor various movements by attaching them to a body have received considerable attention. Crack-based strain sensors are more sensitive than other sensors. Owing to their high sensitivity, these sensors have been investigated for measuring minute deformations occurring on the skin, such as pulse. However, existing studies have limited sensitivity at low strain range and nonlinearity that renders any calibration process complex and difficult. In this study, we propose a pre-strain and sensor-extending process to improve the sensitivity and linearity of the sensor. By using these pre-strain and sensor-extending processes, we were able to control the morphology and alignment of cracks and regulate the sensitivity and linearity of the sensor. Even if the sensor was fabricated in the same manner, the sensor that involved the pre-strain and extending processes had a sensitivity 100 times greater than normal sensors. Thus, our crack-based strain sensor had high sensitivity (gauge factor > 5000, gauge factor (GF = (△R/R0)/ε), linearity, and low hysteresis at low strain (<1% strain). Given its high sensing performance, the sensor can be used to measure micro-deformation, such as pulse wave and voice.

scholarly journals A Practical Strain Sensor Based on Ecoflex/Overlapping Graphene/Ecoflex Sandwich Structures for Vocal Fold Vibration and Body Motion Monitoring

2022 ◽  
Vol 2 ◽  
Author(s):  
Yanyan Fan ◽  
Hongbin Zhao ◽  
Yifan Yang ◽  
Yi Yang ◽  
Tianling Ren ◽  
...  
Keyword(s):  
Structural Design ◽  
Strain Sensor ◽  
Strain Range ◽  
High Sensitivity ◽  
Strain Sensors ◽  
Body Motion ◽  
Gauge Factor ◽  
Sensing Element ◽  
Structure Deformation ◽  
Vocal Fold Vibration

Graphene-based stretchable and flexible strain sensors are one of the promising “bridges” to the biomedical realm. However, enhancing graphene-based wearable strain sensors to meet the demand of high sensitivity, broad sensing range, and recoverable structure deformation simultaneously is still a great challenge. In this work, through structural design, we fabricated a simple Ecoflex/Overlapping Graphene/Ecoflex (EOGE) strain sensor by encapsulating a graphene sensing element on polymer Ecoflex substrates using a drop-casting method. The EOGE strain sensor can detect stretching with high sensitivity, a maximum gauge factor of 715 with a wide strain range up to 57%, and adequate reliability and stability over 1,000 cycles for stretching. Moreover, the EOGE strain sensor shows recoverable structure deformation, and the sensor has a steady response in the frequency disturbance test. The good property of the strain sensor is attributed to the resistance variation induced by the overlap and crack structure of graphene by structural design. The vibrations caused by sound and various body movements have been thoroughly detected, which exhibited that the EOGE strain sensor is a promising candidate for wearable biomedical electronic applications.

Superhydrophobic gradient wrinkle strain sensor with ultra-high sensitivity and broad strain range for motion monitoring

2021 ◽  
Vol 9 (15) ◽  
pp. 9634-9643
Author(s):  
Zhenming Chu ◽  
Weicheng Jiao ◽  
Yifan Huang ◽  
Yongting Zheng ◽  
Rongguo Wang ◽  
...  
Keyword(s):  
Human Body ◽  
Full Range ◽  
Strain Sensor ◽  
Strain Range ◽  
High Sensitivity

A graphene-based gradient wrinkle strain sensor with a broad range and ultra-high sensitivity was fabricated by a simple pre-stretching method. It can be applied to the detection of full-range human body motions.

scholarly journals Understanding the Impact of Machine Learning Models on the Performance of Different Flexible Strain Sensor Modalities

2021 ◽  
Vol 8 ◽  
Author(s):  
Brett C. Hannigan ◽  
Tyler J. Cuthbert ◽  
Wanhaoyi Geng ◽  
Mohammad Tavassolian ◽  
Carlo Menon
Keyword(s):  
Machine Learning ◽  
Mean Squared Error ◽  
Strain Sensor ◽  
High Sensitivity ◽  
Signal Amplitude ◽  
Electrical Signal ◽  
Gauge Factor ◽  
Piezoresistive Sensor ◽  
Fibre Strain ◽  
The Impact

Fibre strain sensors commonly use three major modalities to transduce strain—piezoresistance, capacitance, and inductance. The electrical signal in response to strain differs between these sensing technologies, having varying sensitivity, maximum measurable loading rate, and susceptibility to deleterious effects like hysteresis and drift. The wide variety of sensor materials and strain tracking applications makes it difficult to choose the best sensor modality for a wearable device when considering signal quality, cost, and difficulty of manufacture. Fibre strain sensor samples employing the three sensing mechanisms are fabricated and subjected to strain using a tensile tester. Their mechanical and electrical properties are measured in response to strain profiles designed to exhibit particular shortcomings of sensor behaviour. Using these data, the sensors are compared to identify materials and sensing technologies well suited for different textile motion tracking applications. Several regression models are trained and validated on random strain pattern data, providing guidance for pairing each sensor with a model architecture that compensates for non-ideal effects. A thermoplastic elastomer-core piezoresistive sensor had the highest sensitivity (average gauge factor: 12.6) and a piezoresistive sensor of similar construction with a polyether urethane-urea core had the largest bandwidth, capable of resolving strain rates above 300% s−1 with 36% signal amplitude attenuation. However, both piezoresistve sensors suffered from larger hysteresis and drift than a coaxial polymer sensor using the capacitive strain sensing mechanism. Machine learning improved the piezoresistive sensors’ root-mean-squared error when tracking a random strain signal by up to 58% while maintaining their high sensitivity, bandwidth, and ease of interfacing electronically.

Sign in / Sign up

Export Citation Format

Share Document