Download or read book Flexible pressure and temperature sensors towards e skin material mechanism structure and fabrication written by Shengrui Tian and published by OAE Publishing Inc.. This book was released on 2023-08-07 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electronic skin (E-skin) has gained significant attention due to its potential applications in the Internet of Things (IoT), artificial intelligence (AI), and flexible multi-sensing systems. Mimicking human skin, e-skin sensing devices can be employed in various scenarios. Among the most important sensing elements for tactile e-skin sensors are pressure and temperature sensors, which have increasingly garnered research interest over the past few decades. However, the design and fabrication of advanced pressure and temperature sensors can be challenging owing to complications such as signal interference, complex mechanism integration, and structural design issues. This review provides an overview of flexible pressure and temperature sensors used in e-skin, covering four main perspectives: material selection, mechanism integration, structural design, and manufacturing methods. The materials of different elements in the entire sensing system are comprehensively discussed, along with single and compound mechanisms of pressure and temperature sensing. Pressure and temperature sensors are divided into two types based on their electric output signals, which are exemplified in detail. The manufacturing methods used to fabricate these sensors, including printing methods, are outlined. Lastly, a summary of the future challenges faced by flexible pressure and temperature sensors used in e-skin is presented.

Download or read book Organic Sensors written by Eduardo Garcia-Breijo and published by IET. This book was released on 2016-11-25 with total page 309 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic Sensors: Materials and Applications features contributions from an international panel of leading researchers in organic electronics and their applications as sensors. It reviews the state-of-the-art in the use of organic electronic materials such as organic semiconductors, conducting polymers, chemically functionalized materials, and composite materials as physical, chemical and biomedical sensors in a variety of application settings. Topics covered include organic semiconductors for chemical and physical sensing; conducting polymers in sensor applications; chemically functionalized organic semiconductors for highly selective sensing; composite organic-inorganic sensors; artificial skin applications; organic thin film transistor strain gauges for biomedical applications; OTFT infrared sensors for touchless human-machine interaction; smart fabric sensors and e-textile technologies; image capture with organic sensors; organic gas sensors and electronic noses; electrolyte gated organic transistors for biochemical sensing; ion-selective organic electrochemical transistors; DNA biosensors; metabolic organic sensors; and conductive polymer-based sensors for biomedical applications. This book is cross-disciplinary in its approach and combines electronic engineering, materials science, chemistry, physics and healthcare technology. It will be an invaluable resource for researchers working in sensors and organic electronics.

Download or read book Flexible and Stretchable Medical Devices written by Kuniharu Takei and published by John Wiley & Sons. This book was released on 2018-02-12 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book introduces flexible and stretchable wearable electronic systems and covers in detail the technologies and materials required for healthcare and medical applications. A team of excellent authors gives an overview of currently available flexible devices and thoroughly describes their physical mechanisms that enable sensing human conditions. In dedicated chapters, crucial components needed to realize flexible and wearable devices are discussed which include transistors and sensors and deal with memory, data handling and display. Additionally, suitable power sources based on photovoltaics, thermoelectric energy and supercapacitors are reviewed. A special chapter treats implantable flexible sensors for neural recording. The book editor concludes with a perspective on this rapidly developing field which is expected to have a great impact on healthcare in the 21st century.

Download or read book Additive Manufacturing with Functionalized Nanomaterials written by Sunpreet Singh and published by Elsevier. This book was released on 2021-04-09 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: The greatest benefits of nanoscale additive manufacturing lie in biomedicine, smart devices/sensors, energy harvesting, aerospace, and manufacturing. This book explores the recent applications of functionalized nanomaterials-based additive manufacturing to benefit different manufacturing domains, including design and process aspects, as well as outlining major application areas. This book summarizes recent progress of functionalized nanomaterials-based additive manufacturing on both an experimental and a theoretical model level. Though nanomaterials can be fabricated by bottom-up and top-down approaches (techniques include lithography, photolithography, and micro-machining), the applications of additive manufacturing processes are increasing at an exponential rate and therefore, the demand for high-performance materials has been greatly increasing. Recent applications covered in this book include biomedicine, aerospace, automobile, waste recycling, and energy storage devices. Environmental, regulatory and safety issues are also discussed. This book is an important reference source for materials scientists and engineers who are seeking to improve their understanding of how functionalized nanomaterials are playing an increasingly important role in the additive manufacturing process. Brings together recent innovations and practices of nanomaterials in additive manufacturing processes Outlines major nanomaterials-based additive manufacturing techniques Discusses major applications in a range of industry sectors, including in energy, automotive and biomedicine

Download or read book Printed Flexible Sensors written by Anindya Nag and published by Springer. This book was released on 2019-03-11 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents recent advances in the design, fabrication and implementation of flexible printed sensors. It explores a range of materials for developing the electrode and substrate parts of the sensors, on the basis of their electrical and mechanical characteristics. The sensors were processed using laser cutting and 3D printing techniques, and the sensors developed were employed in a number of healthcare, environmental and industrial applications, including: monitoring of physiological movements, respiration, salinity and nitrate measurement, and tactile sensing. The type of sensor selected for each application depended on its dimensions, robustness and sensitivity. The sensors fabricated were also embedded in an IoT-based system, allowing them to be integrated into real-time applications.

Download or read book Robotic Tactile Sensing written by Ravinder S. Dahiya and published by Springer Science & Business Media. This book was released on 2012-07-29 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Future robots are expected to work closely and interact safely with real-world objects and humans alike. Sense of touch is important in this context, as it helps estimate properties such as shape, texture, hardness, material type and many more; provides action related information, such as slip detection; and helps carrying out actions such as rolling an object between fingers without dropping it. This book presents an in-depth description of the solutions available for gathering tactile data, obtaining aforementioned tactile information from the data and effectively using the same in various robotic tasks. The efforts during last four decades or so have yielded a wide spectrum of tactile sensing technologies and engineered solutions for both intrinsic and extrinsic touch sensors. Nowadays, new materials and structures are being explored for obtaining robotic skin with physical features like bendable, conformable, and stretchable. Such features are important for covering various body parts of robots or 3D surfaces. Nonetheless, there exist many more hardware, software and application related issues that must be considered to make tactile sensing an effective component of future robotic platforms. This book presents an in-depth analysis of various system related issues and presents the trade-offs one may face while developing an effective tactile sensing system. For this purpose, human touch sensing has also been explored. The design hints coming out of the investigations into human sense of touch can be useful in improving the effectiveness of tactile sensory modality in robotics and other machines. Better integration of tactile sensors on a robot’s body is prerequisite for the effective utilization of tactile data. The concept of semiconductor devices based sensors is an interesting one, as it allows compact and fast tactile sensing systems with capabilities such as human-like spatio-temporal resolution. This book presents a comprehensive description of semiconductor devices based tactile sensing. In particular, novel Piezo Oxide Semiconductor Field Effect Transistor (POSFET) based approach for high resolution tactile sensing has been discussed in detail. Finally, the extension of semiconductors devices based sensors concept to large and flexile areas has been discussed for obtaining robotic or electronic skin. With its multidisciplinary scope, this book is suitable for graduate students and researchers coming from diverse areas such robotics (bio-robots, humanoids, rehabilitation etc.), applied materials, humans touch sensing, electronics, microsystems, and instrumentation. To better explain the concepts the text is supported by large number of figures.

Download or read book Novel Stretchable Printed Wearable Sensor for Monitoring Body Movement Temperature and Electrocardiogram Along with the Readout Circuit written by Ali Eshkeiti and published by . This book was released on 2015 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: Conformal and stretchable wearable sensors provide vital real time information about individual's health conditions. In this work, Traditional printing methods are used for fabrication of stretchable and wearable sensors which can be mounted on the human skin for the purpose of health tracking. In addition, screen printing technology was utilized to develop a printed and flexible electronic circuit board which can be used as a readout circuit along with fabricated wearable sensors. The dissertation is organized and pursued in three projects. In the first project, screen printing was used to fabricate multi-layer PCBs using printed deposited materials on three distinct substrates. The different characteristics of PET, paper and glass as a substrate for PCBs were analyzed. A method for populating electronic components onto the printed PCB pads was established and demonstrated. Different analysis, such as effect of the roughness of the substrates on the electrical performance of the printed lines and the effect of bending on the resistivity of the printed lines were performed. The capability of the printed hybrid PCB circuit to correctly operate and drive an LCD was shown. In the second project, a new method for fabrication of wavy lines and structures was devised for the formation of stretchable and flexible wearable sensors. Thermoplastic polyurethane was used as a substrate in this project. Different wavy structure designs were printed and analyzed to determine the best design rules. Silver and Carbon Nano Tubes were used for fabrication of wavy lines. The printability, bendability and stretchability of all printed lines were tested and analyzed. Different design rules and parameters such as the ratio of the width of the lines to their radius and the length of the extended line to the diameter of the arc were tested and analyzed. Printed wavy structures using CNTs showed below 35 percent change in the resistance when it was stretched and 50 percent strain was applied on the structure. 40 percent change in the resistance of the lines printed using silver was obtained when 10 percent strain was applied. The results obtained demonstrated that CNTs showed a promising potential to be used for fabrication of strain wearable sensors. In the third project, a novel wearable sensing platform for the detection of disorder in body movement, temperature and ECG was fabricated. Both wavy structure and non-wavy structure were implemented in these devices. Silver and CNTs inks were used for the fabrication of different sensing parts on the PDMS and tattoo paper as substrates. The strain sensor fabricated on tattoo paper and PDMS were tested towards bending of finger to angles of 10, 20, 30 and 40 degree. 3.66 percent, 4.7 percent and 4.18 percent change was observed in the resistance for each step for sensor 1, sensor 2 and sensor 3, respectively, on tattoo paper. The printed sensor on the PDMS demonstrated average change of 2.7percent, 2.2 percent and 2.8 percent for sensor 1, sensor 2 and sensor 3, respectively, for each step of bending of finger. The printed sensor on the PDMS was successfully implemented as a temperature sensor for tracking of skin temperature. Mixture of silver and silicone was used for fabrication of flexible electrocardiogram sensor on PDMS. The devices response demonstrates the feasibility of printed multi-functional wearable sensors for health monitoring applications.

Download or read book Fabrication and Characterization of Thin Film Pressure Sensors Using Novel Materials written by Victor Samoei and published by . This book was released on 2020 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin-film pressure sensors have received widespread attention in recent times due to its ease of manufacture, characterization, and fatigue strength. Commercial fabrication of these sensors is inexpensive and compatible with the current manufacturing technologies. It has been found that the sensitivity of the flexible pressure sensor depends on the sensing pressure, the microstructural dispersion of nanoparticles, and the compatibility of the binder and the nanoparticles. The binder/particle dispersion should be such that it facilitates the formation of a greater number of conduction paths with a slight change in sensing pressure. The objective of this thesis includes the fabrication and characterization of a thin-film pressure sensor using different novel materials. The first material to be investigated was ZnO. ZnO thin-film materials that have received a great deal of attention due to its unique properties of being a semiconductor with wide bandgap and piezoelectric effect. The sensor characteristic of ZnO was compared with barium-titanate (BaTiO3) Gallium arsenic (GaAs) and Polyvinylidene fluoride (PVDF). The second material to be investigated was aluminum-doped zinc oxide (AZO). AZO has attracted a great deal of attention in many applications because of its nontoxicity, abundancy, and lower cost than other materials such as indium tin oxide (ITO). The AZO films were deposited on polyethylene (PE) substrates by a radiofrequency (rf) magnetron sputtering method. The piezoresistive sensor was tested for different pressures in vacuum and gage pressure conditions. The response characteristics indicated that resistance increased with the bending of the AZO layer in both compressive and tensile operation modes. The sensor characteristics exhibited that the AZO piezoresistive sensor can be used to measure ambient pressure quantitatively. This investigation indicated that AZO can be used as an alternative material for the fabrication of pressure sensors. Lastly, the materials that were investigated are carbon black/ Poly (vinylidene fluoride) (CB/PVDF), graphene/PMMA, and graphene/PVDF composites. The conductive CB/PVDF material was prepared by the wet-cast method and deposited into a flexible polyethylene (PE) substrate, while the graphene composites were prepared by the solvent cast method. The surface morphology, crystal structure, and material properties were studied using SEM and X-ray diffraction methods. Sensitivity, response time, and recovery time were analyzed by testing the sample in the deferent pressure range and vibration modes. The repeatability and reproducibility characteristics of the sensor were studied and found that the sensor exhibits excellent characteristics. The sensors were subjected to different loading/unloading pressures. The resistance of the sensor remained stable indicating that the sensor had a high degree of reproducibility.

Download or read book Laser induced Graphene written by Ruquan Ye and published by . This book was released on 2020-11-30 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: LIG is a revolutionary technique that uses a common CO2 infrared laser scriber, like the one used in any machine shop, for the direct conversion of polymers into porous graphene under ambient conditions. This technique combines the preparation and patterning of 3D graphene in a single step, without the use of wet chemicals. The ease in the structural engineering and excellent mechanical properties of the 3D graphene obtained have made LIG a versatile technique for applications across many fields. This book compiles cutting-edge research on LIG by different research groups all over the world. It discusses the strategies that have been developed to synthesize and engineer graphene, including controlling its properties such as porosity, composition, and surface characteristics. The authors are pioneers in the discovery and development of LIG and the book will appeal to anyone involved in nanotechnology, chemistry, environmental sciences, and device development, especially those with an interest in the synthesis and applications of graphene-based materials.

Download or read book Flexible and Wearable Sensors written by Libo Gao and published by Mdpi AG. This book was released on 2023-08 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Special Issue serves as a valuable resource for readers seeking to delve into the exciting field of flexible and wearable electronics and contribute to their further advancements. This Special Issue presents research papers, short communications, and review articles focusing on the following themes: (1) Novel structural designs, material fabrication, signal processing, and modeling of flexible and wearable sensors applying a wide range of mechanisms to flexible and wearable electronics; (2) MEMS techniques used in the production process of wearable and flexible sensors, along with simulation analysis with theoretical modeling; (3) Multiple application scenarios utilizing multivariable flexible and wearable sensor systems.

Download or read book Stretchable Electronics Towards the Fabrication of Organic Sensors for Artificial Skin written by Bastien Marchiori and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stretchable electronics concern electrical and electronic circuits that are elastically or inelastically stretchable by more than a few percents while retaining function. In order to achieve this, devices tend to be laminar and usually thin. Compared with rigid, hard conventional electronic systems in planar formats, stretchable electronic systems can be stretched, compressed, bent, and deformed into arbitrary shapes without electrical or mechanical failure within the circuits. Currently, stretchable electronic systems have many important and emerging applications in new, soft and curved bio-inspired areas, such as tuneable electronic eye cameras or artificial skin capable of mechanically invisible integration onto human skin. These sensors would be integrated on robotic or prosthetic hands to recreate the same sensing capabilities than the skin: touch, pressure and temperature. The aim of this thesis is to identified strategies and materials to make stretchable devices with stretching capabilities similar to the one of the skin (~15%) with performance close to rigid devices. In this purpose, a microfabrication process to fabricate organic sensors has been developed. The devices are based on laser cut bulk metallic stretchable interconnections with maximum elongation of 80% in PDMS matrix. Then, these tools have been used to fabricate a biosensor: the organic electrochemical transistor (OECT). The transistor is based on a conducting polymer and is able to sense physiological signal. A temperature sensor has also been developed, able to sense infrared signal, like the human skin. These devices can stand up to 30% strain and can be integrated into a matrix for artificial skin applications.

Download or read book Cellular and Molecular Neurophysiology written by Constance Hammond and published by Elsevier. This book was released on 2024-06-03 with total page 602 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cellular and Molecular Neurophysiology, Fifth Edition is the only up-to-date textbook on the market that focuses on the molecular and cellular physiology of neurons and synapses. Hypothesis-driven rather than a dry presentation of the facts, the book promotes a real understanding of the function of nerve cells that is useful for practicing neurophysiologists and students in graduate-level courses on the topic alike. This new edition explains the molecular properties and functions of excitable cells in detail and teaches students how to construct and conduct intelligent research experiments. The content is firmly based on numerous experiments performed by top experts in the field. The new edition contains new chapters on recording neuronal activity, iconotrophic and metabotropic receptors for sensory transduction, and a section containing exercises for further learning. This book will be a useful resource for neurophysiologists, neurobiologists, neurologists, and students taking graduate-level courses on neurophysiology. Authoritative foundational coverage of basic cellular and molecular neurophysiology Includes new chapters on recording neuronal activity, iconotrophic and metabotropic receptors for sensory transduction Provides fifteen appendices that describe how neurobiological techniques are interspersed in the text Presents enhanced coverage of new methodologies and experimental techniques

Download or read book Development of Smart Wearable Sensory Systems on Flexible and Fabric Platforms for Health Monitoring Applications written by Simin Masihi and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wearable sensing technology has recently received an increased attention in both research and commercialization phases and has moved from a vision of science fiction to reality with a wide variety of applications. This incredible growth can be attributed to several factors, such as affordability and ergonomics provided by advances in flexible electronics. The other factors that realized wearable sensing technology include a critical need for more accessible health care services experienced during the recent COVID pandemic, integration to the Internet of Things (IoT), and a growing consumer desire for health awareness. This dissertation presents the fulfillment of three main projects and focuses on the development of various sensors on flexible platforms such as fabrics and plastics using Flexible Hybrid Electronics (FHE) technology to facilitate healthcare monitoring. In the first project, highly sensitive fabric-based pressure sensors were developed for detecting and decreasing sport-related head injuries. Many athletes, from football players to equestrians, rely on helmets (headgear) to protect their heads from impacts or falls. However, a loose or improperly fitted helmet could leave them vulnerable to traumatic brain injuries (TBIs), a leading cause of death or disability in the U.S. To monitor the helmet fit, a highly sensitive pressure sensor cap has been developed that can map pressure in real-time. When worn under a helmet, the cap could help reveal whether the helmet is a perfect fit. These pressure sensors rely on a capacitive mechanism and were fabricated by placing a novel porous polydimethylsiloxane (PDMS) layer between two fabric electrodes. The porous PDMS dielectric layer was fabricated by introducing nitric acid (HNO3) into a mixture of PDMS and sodium bicarbonate (NaHCO3, known as baking soda) to facilitate the liberation of carbon dioxide (CO2) gas, which induces the creation of porous microstructures within the PDMS dielectric layer. This porous PDMS material experiences large deformation, when compared to a solid PDMS layer, and thus increases the capacitance change, making the pressure sensors highly sensitive. In the second project, a flexible wireless electrocardiogram (ECG) device was developed on a fabric platform for electrocardiographic examinations without the use of skin treatments or adhesive gels. In practice, this ECG device facilitates more frequent “at-home” screening of patients who are at risk of cardiovascular disease. The developed device consists of dry electrodes that were fabricated by printing a conductive carbon-PDMS composite on stretchable thermoplastic polyurethane (TPU) laminated on fabric and a flexible readout module that can be directly integrated into clothing. Even though dry electrodes do not use adhesive gel, they perform very similar to conventional wet electrodes and even better in terms of signal to noise ratio. Therefore, they are easier to apply and can potentially replace the wet electrodes. In the third project, a flexible tunable and compact microstrip antenna with a conformal structure was developed for wearable applications. The antenna was fabricated by sandwiching a flexible polyimide substrate between two flexible copper tapes, forming the radiating patch and ground plane. Laser machining was introduced as a facile and fast method for the antenna fabrication. To meet the crucial need of miniaturization of devices in wearables, the antenna was compacted from 2.4 GHz to 900 MHz frequency, without increasing the size of the antenna. Mechanical characterization of the flexible antenna demonstrated the feasibility of the fabricated antenna to sense various bending and stretching stresses.

Download or read book Flexible Electronics written by William S. Wong and published by Springer Science & Business Media. This book was released on 2009-04-09 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt: This excellent volume covers a range of materials used for flexible electronics, including semiconductors, dielectrics, and metals. The functional integration of these different materials is treated as well. Fundamental issues for both organic and inorganic materials systems are included. A corresponding overview of technological applications, based on each materials system, is presented to give both the non-specialist and the researcher in the field relevant information on the status of the flexible electronics area.

Download or read book Smart Sensor Systems written by Gerard Meijer and published by John Wiley & Sons. This book was released on 2014-04-02 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: With contributions from an internationally-renowned group of experts, this book uses a multidisciplinary approach to review recent developments in the field of smart sensor systems, covering important system and design aspects. It examines topics over the whole range of sensor technology from the theory and constraints of basic elements, physics and electronics, up to the level of application-orientated issues. Developed as a complementary volume to ‘Smart Sensor Systems’ (Wiley 2008), which introduces the basics of smart sensor systems, this volume focuses on emerging sensing technologies and applications, including: State-of-the-art techniques for designing smart sensors and smart sensor systems, including measurement techniques at system level, such as dynamic error correction, calibration, self-calibration and trimming. Circuit design for sensor systems, such as the design of precision instrumentation amplifiers. Impedance sensors, and the associated measurement techniques and electronics, that measure electrical characteristics to derive physical and biomedical parameters, such as blood viscosity or growth of micro-organisms. Complete sensor systems-on-a-chip, such as CMOS optical imagers and microarrays for DNA detection, and the associated circuit and micro-fabrication techniques. Vibratory gyroscopes and the associated electronics, employing mechanical and electrical signal amplification to enable low-power angular-rate sensing. Implantable smart sensors for neural interfacing in bio-medical applications. Smart combinations of energy harvesters and energy-storage devices for autonomous wireless sensors. Smart Sensor Systems: Emerging Technologies and Applications will greatly benefit final-year undergraduate and postgraduate students in the areas of electrical, mechanical and chemical engineering, and physics. Professional engineers and researchers in the microelectronics industry, including microsystem developers, will also find this a thorough and useful volume.

Download or read book Cognitive Systems written by Henrik Christensen and published by Springer Science & Business Media. This book was released on 2010-04-05 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt: Design of cognitive systems for assistance to people poses a major challenge to the fields of robotics and artificial intelligence. The Cognitive Systems for Cognitive Assistance (CoSy) project was organized to address the issues of i) theoretical progress on design of cognitive systems ii) methods for implementation of systems and iii) empirical studies to further understand the use and interaction with such systems. To study, design and deploy cognitive systems there is a need to considers aspects of systems design, embodiment, perception, planning and error recovery, spatial insertion, knowledge acquisition and machine learning, dialog design and human robot interaction and systems integration. The CoSy project addressed all of these aspects over a period of four years and across two different domains of application – exploration of space and task / knowledge acquisition for manipulation. The present volume documents the results of the CoSy project. The CoSy project was funded by the European Commission as part of the Cognitive Systems Program within the 6th Framework Program.

Download or read book Semiconductor Gas Sensors written by Raivo Jaaniso and published by Woodhead Publishing. This book was released on 2019-09-24 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor Gas Sensors, Second Edition, summarizes recent research on basic principles, new materials and emerging technologies in this essential field. Chapters cover the foundation of the underlying principles and sensing mechanisms of gas sensors, include expanded content on gas sensing characteristics, such as response, sensitivity and cross-sensitivity, present an overview of the nanomaterials utilized for gas sensing, and review the latest applications for semiconductor gas sensors, including environmental monitoring, indoor monitoring, medical applications, CMOS integration and chemical warfare agents. This second edition has been completely updated, thus ensuring it reflects current literature and the latest materials systems and applications. Includes an overview of key applications, with new chapters on indoor monitoring and medical applications Reviews developments in gas sensors and sensing methods, including an expanded section on gas sensor theory Discusses the use of nanomaterials in gas sensing, with new chapters on single-layer graphene sensors, graphene oxide sensors, printed sensors, and much more