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Sharma S, Thapa A, Singh S, Mondal T. Crosstalk-free graphene-liquid elastomer based printed sensors for unobtrusive respiratory monitoring. NANOSCALE 2024; 16:3498-3509. [PMID: 38265155 DOI: 10.1039/d3nr04774a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2024]
Abstract
Flexible strain sensors have garnered attraction in the human healthcare domain. However, caveats like crosstalk and noise associated with the output signal of such a sensor often limit the accuracy. Hence, developing a strain sensor via frugal engineering is critical, thereby warranting its mass utility. A stencil printable graphene/liquid elastomeric crosstalk-free strain sensor for unobtrusive respiratory monitoring is reported herein. Printing supports the frugality of the process and avoids complex fabrication. The sensor was mounted on a wearable mask, and the sensor console was fabricated. The console demonstrated the capability to detect the respiratory profile at room and low temperature (-26 °C) with an SNR of -12.85 dB. Developed sensors could nullify the impact of temperature and humidity and generate respiratory signals due to strain induced by breathing. A model experiment was conducted to support the fidelity of the strain mechanism. The console demonstrated excellent stability (over 500 cycles) with a sensitivity of -196.56 (0-0.17% strain) and 117.49 (0.17-0.34% strain). The console could accurately determine conditions like eupnea, tachypnoea, etc., and transmit the data wirelessly via Bluetooth. These findings solve major caveats in flexible sensor development by focusing on selectivity, sensitivity, and stability.
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Affiliation(s)
- Simran Sharma
- Rubber Technology Centre, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
| | - Ankur Thapa
- Rubber Technology Centre, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
| | - Sumit Singh
- Anton Paar India Pvt. Ltd, Gurgaon, 122016, India
| | - Titash Mondal
- Rubber Technology Centre, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
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Guchait A, Sharma S, Chattopadhyay S, Mondal T. Synthesis of gallic acid-grafted epoxidized natural rubber and its role in self-healable flexible temperature sensors. SOFT MATTER 2023; 20:178-191. [PMID: 38063459 DOI: 10.1039/d3sm01367g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Developing a flexible temperature sensor with appreciable sensitivity is critical for advancing research related to flexible electronics. Although various flexible sensors are available commercially, most such temperature sensors are made from polymeric materials obtained from petrochemical resources. Such sensors will contribute to electronic waste and increase the carbon footprint after usage. While there are reports on various sensors made from sustainable polymers, research related to developing self-healable flexible temperature sensors made from sustainable polymers is significantly less. Herein, we report on developing a flexible temperature sensor made of gallic acid-grafted epoxidized natural rubber and multi-walled carbon nanotubes. Various spectroscopic and thermal techniques vetted the modification of the epoxidized natural rubber. The highest grafting of 20.9% was achieved in the selected window of stoichiometry. A self-healing behavior was achieved by leveraging the FeCl3 based metal-ligand crosslinking of the composite. The healing efficiency was noted to be 31.2% for the composite material. The fabricated sensor demonstrated an electrical resistance of 4.46 × 103 Ω, thereby warranting the composite to demonstrate an Ohmic behavior in the I-V plot. Appropriate data fitting suggested a variable range hopping mechanism as causation towards excellent electrical conduction. The temperature sensitivity and the thermal index of the developed sensor were noted to be -0.17% °C-1 and 781.2 K, respectively, in the temperature range of 30 °C to 50 °C. The proposed method of fabricating sustainable, high-strength, self-healable, and robust temperature sensors and conductors is a unique and value-added approach for next-generation flexible electronics.
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Affiliation(s)
- Aparna Guchait
- Rubber Technology Centre, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India.
| | - Simran Sharma
- Rubber Technology Centre, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India.
| | - Santanu Chattopadhyay
- Rubber Technology Centre, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India.
| | - Titash Mondal
- Rubber Technology Centre, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India.
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Li Y, Jin Y, Zeng W, Jin H, Shang X, Zhou R. Bioinspired Fast Room-Temperature Self-Healing, Robust, Adhesive, and AIE Fluorescent Waterborne Polyurethane via Hierarchical Hydrogen Bonds and Use as a Strain Sensor. ACS APPLIED MATERIALS & INTERFACES 2023; 15:35469-35482. [PMID: 37462218 DOI: 10.1021/acsami.3c05699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
Developing a new generation of ecofriendly water-based polymeric materials that integrate mechanical robustness, fast room-temperature self-healing, adhesive, and fluorescence remains a formidable challenge. Herein, inspired by titin protein, a series of novel waterborne polyurethanes (WPU-CHZ-NAGA) containing irregular 6-fold and diamide hydrogen bonds are synthesized by introducing carbohydrazide (CHZ) and N,N-bis(2-hydroxyethyl)-3-amino propionyl glycinamide (HO-NAGA-OH) groups. The representative WPU-CHZ2-NAGA3 exhibits outstanding mechanical properties (tensile strength of 36.58 MPa, tearing energy of 81.2 kJ m-2, and toughness of 125.82 MJ m-3) and fast room-temperature self-healing ability with the aid of ethanol (≥90% within 8 h) originated from hierarchical hydrogen bonds. These properties are superior to those of most of the reported room-temperature self-healing polymer materials. Benefiting from plentiful hydrogen bonds, the WPU matrix achieves excellent adhesive properties without heating or adding curing agents. Interestingly, WPU-CHZ2-NAGA3 film emits inherent blue fluorescence due to the aggregation-induced emission effect of tertiary amine groups, and its potential applications in information encryption and anticounterfeiting are further demonstrated. Specially, a eutectic gel strain sensor is also fabricated with WPU-CHZ2-NAGA3 and deep eutectic solvent by a simple physical blending method, which can be used to monitor the movement of human fingers and wrists as well as the change in body temperature. In summary, this work provides new insight into the design and synthesis of multifunctional WPU with fast room-temperature self-healing and high mechanical properties.
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Affiliation(s)
- Yupeng Li
- National Engineering Research Center of Clean Technology in Leather Industry, Sichuan University, Chengdu 610065, China
- Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065, China
| | - Yong Jin
- National Engineering Research Center of Clean Technology in Leather Industry, Sichuan University, Chengdu 610065, China
- Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065, China
| | - Wenhua Zeng
- National Engineering Research Center of Clean Technology in Leather Industry, Sichuan University, Chengdu 610065, China
- Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065, China
| | - Hongyu Jin
- Department of Obstetrics and Gynecology, West China Second University Hospital, Sichuan University, Chengdu 610065, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu 610065, China
| | - Xiang Shang
- National Engineering Research Center of Clean Technology in Leather Industry, Sichuan University, Chengdu 610065, China
- Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065, China
| | - Rong Zhou
- National Engineering Research Center of Clean Technology in Leather Industry, Sichuan University, Chengdu 610065, China
- Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065, China
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Haridas A, Sharma S, Naskar K, Mondal T. Cross-Talk Signal Free Recyclable Thermoplastic Polyurethane/Graphene-Based Strain and Pressure Sensor for Monitoring Human Motions. ACS APPLIED MATERIALS & INTERFACES 2023; 15:17279-17292. [PMID: 36944054 DOI: 10.1021/acsami.3c01364] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Developing a sensor that can read out cross-talk free signals while determining various active physiological parameters is demanding in the field of point-of-care applications. While there are a few examples of non-flexible sensors available, the management of electronic waste generated from such sensors is critical. Most of such available sensors are rigid in form factor and hence limit their usability in healthcare monitoring due to their poor conformity to human skin. Combining these facets, studies on the development of a recyclable cross-talk free flexible sensor for monitoring human motions and active parameters are far and few. In this work, we report on the development of a recyclable flexible sensor that can provide accurate data for detecting small changes in strain as well as pressure. The developed sensor could decipher the signals individually responsible due to strain as well as pressure. Hence, it can deliver a cross-talk free output. Thermoplastic polyurethane and graphene were selected as the model system. The thermoplastic polyurethane/graphene sensor exhibited a tensile strain sensitivity of GF ≃ 3.375 for 0-100% strain and 10.551 for 100-150% strain and a pressure sensitivity of ∼-0.25 kPa-1. We demonstrate the applicability of the strain sensor for monitoring a variety of human motions ranging from a very small strain of eye blinking to a large strain of elbow bending with unambiguous peaks and a very fast response and recovery time of 165 ms. The signals received are mostly electrical hysteresis free. To confirm the recyclability, the developed sensor was recycled up to three times. Marginal decrement in the sensitivity was noted with recycling without compromising the sensing capabilities. These findings promise to open up a new avenue for developing flexible sensors with lesser carbon footprints.
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Affiliation(s)
- Ajay Haridas
- Rubber Technology Centre, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Simran Sharma
- Rubber Technology Centre, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Kinsuk Naskar
- Rubber Technology Centre, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Titash Mondal
- Rubber Technology Centre, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
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Wang J, Wang Z, Zuo Y, Wang W. Multiscale Analysis of the Highly Stretchable Carbon−Based Polymer Strain Sensor. Polymers (Basel) 2023; 15:polym15071780. [PMID: 37050395 PMCID: PMC10097124 DOI: 10.3390/polym15071780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 03/30/2023] [Accepted: 03/31/2023] [Indexed: 04/07/2023] Open
Abstract
In this paper, a multiscale analysis method was proposed to simulate carbon nanoparticles (CNPs)−filled polymers which can be strain sensors applied in wearable electronic devices, flexible skin, and health monitoring fields. On the basis of the microstructure characteristics of the composite, a microscale representative volume element model of the CNPs−filled polymer was established using the improved nearest−neighbor algorithm. By finite element analysis, the variation of the junction widths of adjacent aggregates can be extracted from the simulation results. Then, according to the conductive mechanism of CNP−filled polymers, the composite was simplified as a circuit network composed of vast random resistors which were determined by the junction widths between adjacent aggregates. Hence, by taking junction widths as the link, the resistance variation of the CNPs−filled polymer with the strain can be obtained. To verify the proposed method, the electromechanical responses of silicone elastomer filled with different CNPs under different filling amounts were investigated numerically and experimentally, respectively, and the results were in good agreement. Therefore, the multiscale analysis method can not only reveal the strain−sensing mechanism of the composite from the microscale, but also effectively predict the electromechanical behavior of the CNPs−filled polymer with different material parameters.
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Affiliation(s)
- Junpu Wang
- College of Mechanical and Electrical Engineering, Shaanxi University of Science and Technology, Xi’an 710021, China
| | - Zhu Wang
- College of Mechanical and Electrical Engineering, Shaanxi University of Science and Technology, Xi’an 710021, China
| | - Yanjiang Zuo
- College of Mechanical and Electrical Engineering, Shaanxi University of Science and Technology, Xi’an 710021, China
| | - Wenzhi Wang
- School of Aeronautics, Northwestern Polytechnical University, Xi’an 710072, China
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