Periodic Reporting for period 1 - FLEXI-G (TOWARDS A NOVEL HIGH PERFORMANCE FLEXIBLE GMR SENSOR ON PAPER)
Reporting period: 2018-07-01 to 2020-06-30
Over the last decade, advances in the field of flexible electronics have reinvigorated the global electronics industry. The new features such as flexibility, conformability and disposability etc. of this new generation electronics have been made possible with fabrication of electronics directly on non-conventional substrates such as paper and plastic etc. The possibility of having electronics on paper and plastic also opens opportunities for innovative use of electronics in challenging areas such as counterfeit currency.
Magnetic transducers are widely used in modern industry and electronics to sense the magnetic field strength to measure current, position, motion, direction, and other physical parameters. Recent progresses of Giant Magnetic Resistance (GMR) has opened a new opportunity as it allows controlling an electronic device in non-contact mode by means of localized magnetic fields. The GMR sensors are particularly interesting as the resistance of their ferromagnetic layers can be altered by external magnetic field, which can be used to trigger the electronic circuits. The integration of GMR components onto a flexible device requires overcoming several practical challenges. These include relatively lower GMR response compared to rigid counterparts, performance instability due to elastic mismatch when deformed, induced strain effects due to substrate roughness, and higher anisotropy and switching fields of magnetic free layer causing interference with other coupled components etc.
This proposed project will realize GMR sensor on paper surpassing these difficulties and provide a breakthrough towards novel applications such as preventing currency counterfeits. The magnetic sensing devices developed by the proposed approach also could advance in the area of magnetic sensors for flexible electronics and soft robotics which is challenging with conventional approaches. The research also can also provide more scientific understanding on the fundamentals of magnetic materials and devices.
The major goals of the project are
(1) synthesize and characterize controlled composition of nanoparticles for example FeCo and Cu
(2) develop GMR by printing multiple alternate layers of the nanoparticles on paper
(3) integrate the paper-GMR sensor with other electronic components on flexible substrates and
(4) demonstrating the efficacy of proposed system in different applications including the detection of counterfeit currency.
Magnetic transducers are widely used in modern industry and electronics to sense the magnetic field strength to measure current, position, motion, direction, and other physical parameters. Recent progresses of Giant Magnetic Resistance (GMR) has opened a new opportunity as it allows controlling an electronic device in non-contact mode by means of localized magnetic fields. The GMR sensors are particularly interesting as the resistance of their ferromagnetic layers can be altered by external magnetic field, which can be used to trigger the electronic circuits. The integration of GMR components onto a flexible device requires overcoming several practical challenges. These include relatively lower GMR response compared to rigid counterparts, performance instability due to elastic mismatch when deformed, induced strain effects due to substrate roughness, and higher anisotropy and switching fields of magnetic free layer causing interference with other coupled components etc.
This proposed project will realize GMR sensor on paper surpassing these difficulties and provide a breakthrough towards novel applications such as preventing currency counterfeits. The magnetic sensing devices developed by the proposed approach also could advance in the area of magnetic sensors for flexible electronics and soft robotics which is challenging with conventional approaches. The research also can also provide more scientific understanding on the fundamentals of magnetic materials and devices.
The major goals of the project are
(1) synthesize and characterize controlled composition of nanoparticles for example FeCo and Cu
(2) develop GMR by printing multiple alternate layers of the nanoparticles on paper
(3) integrate the paper-GMR sensor with other electronic components on flexible substrates and
(4) demonstrating the efficacy of proposed system in different applications including the detection of counterfeit currency.
During the fellowship, various materials, methods and approaches for sensing in flexible magnetic systems was explored. FeCo and Cu nanoparticles has been successful synthesized by chemical methods and characterized for magnetic sensing applications. The properties of these materials also has been studied and their suitability for sensing applications has been analysed. Along with flexible electronics, the choice of methodology was adopted in a way to utilize them for soft robotic and wearable applications. In this regard, the research also has provided new directions in the area of soft robotics. Various approaches for fabrication of soft robotic devices were explored and potential routes to design highly stretchable and flexible soft robots and sensors were evolved. For various applications, piezoresistive strain sensors were developed with high performance metrices such as ultrastretchability, high gauge factor (>4000) and sensitivity of the order of 15k. These sensors were potentially demonstrated for various applications such as closed loop controlled Bioinspired soft robots , respiratory monitoring, haptic interfaces, tactile sensing etc.
The outcomes of the research shows progress beyond state of art. The research has provided new insights to the chemical synthesis of nanoparticles and various parameters influencing them. The project also explored the potential development of highly sensitive strain sensors which are industrially on demand for robotic and flexible electronic applications. Considering the impact of Covid-19, the sensor was potentially demonstrated for use of fabric based respiratory monitoring wearables with performance superior to those reported so far. . The piezoresistive strain sensing mechanism has been studies in detail and a better understanding of the hysteresis phenomena was achieved. The research also helped to understand various challenges in soft robotics, flexible electronic sensing etc. Based on the research, bioinspired closed loop controlled magnetic soft robots was demonstrated while most of the state-of-art soft robots are open loop controlled. This outcome if expected to contribute to the advancement of magnetic soft robotics. The research also has provided new results towards printed sensors for flexible electronic applications.