Essay on Flexible Electronics Technology


Introduction:

Flexible electronics can be termed as assembling of electrical circuits on thin flexible substrates like plastic or metallic foil. It is made up of two layers where the first layer is of thin substrate which can be passed on and built on it is another layer of electronic components which are active. It may also consist of few more layers for further resistance and packaging. (Alam & Kumar, n.a)
With the advancement of technology, there is an increasing urge to develop products which use nano technology and provide more flexibility. We are going to observe various factors regarding Flexible Electronics.
Emerging technology: Flexible Electronics

The development of flexible electronics took place on a wide scale before 40 years with the invention of flexible arrays of solar cell which were made from extremely thin crystals of silicon on plastic substrates which is nowadays replaced by organic light emitting diode emitted on plastic substrates and this is a current example of flexible electronics. (Wong & Alberto, 2009) This development is also favoured by technological advancements in thin film materials and devices and also the various circuits on which it substrates. This progress has been supported by the advancements and adaptation of new integration processes which has enabled the combination of this thin circuits on their flexible substrates. (Nathan, Lee, Suzuki, & Bonaccorso,, 2012)
Flexible electronics is mainly developing in generation of Carbon Nano Tubes circuits (CNTs) and thin Film Transistors (TFTs) which are broadly used in the industrial field for many purposes. (Cheng & Wagner, 2009)

Capabilities of Flexible electronics:

Flexible electronics plays a very important role in the development of printing technologies which can largely affect many industries. For this purpose, roll–to–roll lithography systems has been developed. (Jain, Klosner, Zemel, & Raghunandan, 2005)

CNTs are highly adaptive, have high conductivity and provide transparency in the spectrum and this makes them suitable in applications such as arrays of solar cells and flexible screen displays. TFTs produced with the help of Transition metal oxides (TMOs) or standard Si:H are widely used in the production of image sensors and micro-electro mechanical systems. (Wong & Alberto, 2009)

Factors promoting the growth of Flexible electronics:

The use of flexible electronics is on an increase this days due to the following factors that promote its growth:
• Low profile
• Lighter weight and compact size
• Suitable dielectric properties. (Jain, Klosner, Zemel, & Raghunandan, 2005)
• High performance transistors and circuits used
• Use of inorganic semi-conductors that provide bending and flexibility.
• Fabrication of high quality materials as wires, sheets, bars, etc. (Baca & Ahn, 2008)
• Low cost
• Large area Flexibility and compatibility
• Large scalability
• Seamless integration (Nathan, Lee, Suzuki, & Bonaccorso,, 2012)
Though, the use of this technology has a wide range of advantages, it has few factors that does limit its application in certain devices which are discussed below:
Factors limiting the growth of Flexible electronics:

In case of printing industries, it imposes the problems pertaining to the resolution, size of the panel, distortion of substrate, process throughput and handling of materials along with its yield and the availability of desired output. (Jain, Klosner, Zemel, & Raghunandan, 2005)
In case of Carbon Nano tubes circuits (CNTs), there is a problem of distortion when power fluctuations are observed and this will not let the circuit to work without flaws. The amount of power consumed is also more in CNTs and they cannot adapt to high electrical noises. Due to this reasons, traditional silicon chips proved to be more reliable and power efficient. (Flexible electronics: Flexible carbon nanotube circuits more reliable and power efficient, 2014)
A standard Si:H Thin Film Transistors (TFTs) provides low performance for image sensing in roll-to-roll processes. It affects the mechanical Stability and distorts the multi layered structure of the circuit in low melting plastic substrates. (Wong & Alberto, 2009)

Factors supporting the development of Flexible electronics:

The problem of the printing technology was solved by the development of roll-to-roll lithography systems. These systems have made the projection of high resolution images on extremely huge exposed surfaces including that of the substrates that are flexible. They overcome the issue of substrate distortion with the help of image scaling that has high precision alignment. It also helps to project designs of millions of pixels through the use of project imaging and also helps to achieve good- throughput of the photo ablation. (Jain, Klosner, Zemel, & Raghunandan, 2005)
Engineers have derived that a circuit will be consuming less power and be more reliable when it will be a combination of P- type and N-type semiconductors both, whereas CNTs are initially P- type semiconductors. A team of researchers from the Stanford University used a dopant called as DMBI to add N-type semiconductors characteristics. They deposited this dopant material on calculated locations on the circuit with the help of an inkjet printer. This will help the development of CNT circuits to make flexible and rigid circuits. (Wang, Bao, & Gao, 2014)
Using Transition metal oxides (TMOs) in place of Si:H for production of TFTs will increase its performance and provide better stability. (Wong & Alberto, 2009) This will also provide a good base for image sensing as well as in the printing process where these transistors are used for imprinting.

Challenges emerging in Flexible electronics:

Production of flexible circuits for electronics is affordable only for large scale production and precision based applications and is limited for applications which involves use of high resolution and requires unaffected substrates. (Jain, Klosner, Zemel, & Raghunandan, 2005)
There is a wide scope of development which is possible in the production of CFTs as doped by the Stanford team and it has to go through many advancements before its commercialization. It still has to undergo many modifications before being used on a commercial scale.(Flexible electronics: Flexible carbon nanotube circuits more reliable and power efficient, 2014)

Sectors benefitted by Flexible electronics:

The development of flexible electronics in printing technique is favourable for flexible circuit boards and flexible chip carriers. They also have a rising potential in the production of flexible displays as well as in macro electronic systems. (Jain, Klosner, Zemel, & Raghunandan, 2005)
CNT circuits are used on a wide scale, nowadays in production of display tubes. The doping process developed and proposed by the Stanford team helps to achieve the required P-N combination in the CNTs which will make them more power efficient and reliable. CNTs not only provide the bending and flexible characteristics of the Standard plastic circuits, but also provide the ability to deliver rapid performance. (Flexible electronics: Flexible carbon nanotube circuits more reliable and power efficient, 2014)
Use of the Transition Metal oxides (TMOs) in creating Thin Film Transistors (TFTs) will provide more accuracy and precision and hence can be used in imprinting lithography and various flexible image sensing applications. (Wong & Alberto, 2009)

Conclusion:

Wearable technology (WT) requires a precise control in making of garments, imprinting, imaging sensors, less power consumption, appropriate semi-conductors, control of substrates and integrable multiple sensing devices. (Manufacturers and Supply Chain Companies Gear Up for Flexible Electronics, 2014)
Flexible electronics also has a great future in the Wearable Technology (WT) where there is a generation striving for nano technology and flexibility pertaining to the wide scale demand of flexible wearable gadgets. (Meyer, 2014)

References
Baca, A. (2008, july 10). Semiconductor Wires and Ribbons for High- Performance Flexible Electronics. Retrieved July 13, 2014, from http://onlinelibrary.wiley.com/: http://onlinelibrary.wiley.com/doi/10.1002/anie.200703238/abstract;jsessionid=8D0B01579342389E2B9B83ADA04ACAF3.f04t02?deniedAccessCustomisedMessage=&userIsAuthenticated=false
Cheng, I.-C., & Wagner, S. (2009). Overview of Flexible Electronics Technology. Retrieved July 19, 2014, from http://link.springer.com/: http://link.springer.com/chapter/10.1007/978-0-387-74363-9_1
Flexible electronics: Flexible carbon nanotube circuits more reliable and power efficient. (2014, march 17). Retrieved July 13, 2014, from http://www.sciencedaily.com: http://www.sciencedaily.com/releases/2014/03/140317155619.htm
Jain, K. (2005, july 18). Flexible Electronics and Displays: High-Resolution, Roll-to-Roll, Projection Lithography and Photoablation Processing Technologies for High-Throughput Production. Retrieved july 19, 2014, from http://ieeexplore.ieee.org/: http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=1468607&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D1468607
Manufacturers and Supply Chain Companies Gear Up for Flexible Electronics. (2014). Retrieved july 19, 2014, from www.flexconference.org: http://www.flexconference.org/
Meyer, D. (2014, april 7). How thin, flexible electronics will revolutionize everything from user interfaces to packaging. Retrieved july 19, 2014, from http://gigaom.com/: http://gigaom.com/2014/04/07/how-thin-flexible-electronics-will-revolutionize-everything-from-user-interfaces-to-packaging/
Nathan, A., & Lee, S. (2012, may 13). Flexible Electronics: The Next. Retrieved july 19, 2014, from http://www3.eng.cam.ac.uk: http://www3.eng.cam.ac.uk/~mtc35/index_files/Papers/06198376.pdf
Prof.Alam, M. A., & Dr. Kumar, S. (n.d.). Flexible Electronics. Retrieved July 19, 2014, from http://www.springerreference.com/: http://www.springerreference.com/docs/html/chapterdbid/340008.html
Wang, H., & Bao, Z. (2014, february 18). Tuning the threshold voltage of carbon nanotube transistors by n-type molecular doping for robust and flexible complementary circuits. Retrieved july 19, 2014, from http://www.pnas.org: http://www.pnas.org/content/111/13/4776
Wong, W. S., & Alberto, S. (2009). Flexible Electronics: Materials and Applications. Retrieved july 19, 2014, from http://download.springer.com: http://download.springer.com/static/pdf/750/bfm%253A978-0-387-74363-9%252F1.pdf?auth66=1405937404_8ab8abd366679a36fd2282f663490d11&ext=.pdf

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March 10, 2018

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