Thin film electronic devices made using flexible materials, such as plastics, metals, or polymers, are growing in popularity. Their ability to be bent, folded, and rolled as well as being lightweight and durable makes them ideal for a variety of applications, including wearable devices, smart bandages, and foldable displays. They can be manufactured using a variety of techniques, including printing, coating, and lamination. Flexible electronics have a number of potential advantages over traditional electronic devices due to their high performance, low cost, flexibility, and process simplicity.
Plasma treatment often plays a critical role in thin film electronics manufacturing. The benefits of plasma treatment for thin film electronics include:
- Increasing surface roughness, which can improve adhesion between materials. This is important in flexible electronics because it helps to ensure that the different layers of the device adhere to each other properly.
- Creating reactive functional groups, which improve chemical bonding between materials. This can be used to create a surface that is more compatible with other materials, such as adhesives or solvents.
- Removing contaminants from a surface, which can improve the quality of the final product. This is important in flexible electronics because it helps to prevent defects and ensure that the device is functioning properly.
Bioelectronics are a subset of thin film electronics that combine flexible wearable electronics with biomedical applications. One common material used for these devices is poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). Its advantageous properties include high conductivity, chemically stability, low cost, and non-toxic. It is a material well suited for flexible electronics as it is easily moldable into different shapes.
Plasma exposure is used to modify material surfaces prior to the deposition of PEDOT:PSS for the fabrication of these devices. The plasma treatment alters the surface by removing contaminants and increasing its hydrophilicity, altering the surface to be more favorable for spin-coating of the desired layer for flexible electronics.
For example, in Chen et al. 2022, a PDMS substrate was exposed to plasma to render the surface hydrophilic as the coating would not properly adhere otherwise. Following the plasma treatment silver nanowires (AgNWs) and PEDOT:PSS were deposited on the surface. The device fabricated was a “self cleaning flexible wearable temperature sensing device” that allows for real-time temperature monitoring of patients. The monitoring of different health information is a common bioelectronic as it aides in making healthcare more patient-friendly.
Featured Bioelectronics Articles
Chen CH, Tsai TW, Cheng IC, Chen JZ. “Superhydrophobic, Oleophobic, Self-Cleaning Flexible Wearable Temperature Sensing Device”. ECS Advances (2022) 1: 036502. 10.1149/2754-2734/ac82bf 10.1149/2754-2734/ac82bf
Chen H, Yang W, Zhang C, Wu M, Li W, Zhou Y, Lv L, Yu H, Ke H, Liu R, Xu Y, Wang J, Li Z. “Performance-enhanced and cost-effective triboelectric nanogenerator based on stretchable electrode for wearable SpO2 monitoring”. Nano Research (2022) 15: 2465-2471. 10.1007/s12274-021-3724-1
As thin film electronics continue to grow in popularity, so do the variety of materials used for their fabrication. These materials include graphene, polydimethylsiloxane (PDMS), and carbon nanotubes (CNTs). Recent articles have cited the usage of Harrick Plasma devices to create a variety of thin film electronics:
- Thin film wearable heaters were fabricated to improve upon the current rigid and heavy heaters used for therapeutic care. Silica and indium-tin-oxide (ITO) substrates were plasma treated and then coated with PDMS. The pretreatment with the plasma promoted the covalent binding of the thin films to the cured PDMS layer. (Ding and Moran-Mirabel 2022)
- A graphene-based wearable electronic device was developed to monitor subtle skeletal muscle movements for disease diagnostics. The device was comprised of an ultrasoft, super-compressible graphene-based cellular material (UGCM), and a problem arose when the UGM was mechanically tested failures formed easily. In order to fix this issue, two PDMS pieces were plasma treated and bonded to the UGCM so that it was sandwiched. This alteration prevented the failures in the material, allowing the device to be suitable for wearing. (He et al. 2022)
Other Device Articles
Abunala H, Zafar H, Anjum D, Alazzam A, Mohammad B. “Enhanced Graphene Oxide Electrical Properties for Thin-Film Electronics Using an Active/Shrinkable Substrate”. ACS Omega (2023) 8: 1671-1676. 10.1021/acsomega.2c07306
Ding X, Moran-Mirabal J. “Efficient Multi-Material Structured Thin Film Transfer to Elastomers for Stretchable Electronic Devices”. Micromachines (2022) 13. 10.3390/mi13020334
He Z, Qi Z, Liu H, Wang K, Roberts L, Liu J, Wang S, Cook M, Simon G, Qiu L, Li D. “Detecting subtle yet fast skeletal muscle contractions with ultrasoft and durable graphene-based cellular materials”. National Science Review (2022) 9: nwab184. 10.1093/nsr/nwab184
Khakbaz H, Ruberu K, Kang L, Talebian S, Savyar S, Filippi B, Khatamifar M, Beirne S, Innis P. “3D printing of highly flexible, cytocompatible nanocomposites for thermal management”. Journal of Materials Science (2021) 56. 10.1007/s10853-020-05661-9
Supplemental Articles (Not Featuring Harrick Plasma Cleaners)
Sahoo BN, Janghoon W, Algadi H, Lee J, Lee T. “Superhydrophobic, Transparent, and Stretchable 3D Hierarchical Wrinkled Film-Based Sensors for Wearable Applications”. Advanced Materials Technologies (2019) 4: 1900230. 10.1002/admt.201900230