A materials scientist is investigating the reasons why certain household cleaners can damage the protective coating on the screen of a smartphone.
To curb the spread of the Covid-19 virus, public health experts have highlighted the importance of frequent hand washing and the need to clean and disinfect frequently affected surfaces. But what about our smartphones and other personal electronic devices that we touch during the day?
Many smartphone manufacturers do not recommend the use of cleaning agents or disinfectants for cleaning touchscreens, although some have updated their tips. Robert Macfarlane , Paul M. Cook, assistant professor of materials science and engineering at MIT , is developing new techniques for manufacturing self-organizing materials that can be used to make protective coatings, adhesives, sensors, and more. Device Types He explained to MIT News why certain cleaning products could affect the operation of a smartphone screen, how the screen of his phone can be disinfected and how touch screens with antimicrobial properties can be designed.
Professor Rob MacFarlane is a professor of materials science and engineering at MIT. Photo credit: Lillie Paquette, MIT School of Engineering
Q : Many people want to disinfect their smartphones and other personal electronic devices to stop Covid-19 from spreading. Experts recommend using water and soap or disinfectant wipes to clean surfaces. But can these cleaning products damage your phone's screen?
A : Every time we touch our phones or a surface, a certain amount of material in our hands is transferred to the affected surface. In addition, a certain amount of material sticks to our hands on the surface we touch. Therefore we have to wash our hands constantly to prevent the spread of Covid-19. The amount transferred varies depending on the actual composition of the surface, and we can modify or minimize the amount of residue left on a surface by covering it with a material that does not have a strong chemical attraction to the materials on our fingers. The residue of our fingers consists of a variety of substances such as water or various salts, but most of them consist of oils. By applying an "oleophobic" coating to a surface, a material that has no strong affinity for binding to oily substances, the amount of remaining oils is minimized.
Oleophobic coatings generally consist of fluorinated or fluorocarbon polymers, which are classes of molecules that do not have a really strong binding affinity for water-soluble or oil-soluble materials. While the use of rubbing alcohol or an alcohol-based wipe is unlikely to completely remove this coating, prolonged exposure to highly concentrated alcohols can alter this coating by removing small fluorocarbon stains or changing the distribution of the coating so that it is not be completely uniform. on a surface Without a uniform coating to prevent material adhesion, residues stick much more often. This affects the optical properties of the device. For example, stains could appear that would make it difficult to see through the coating. This can also affect the mechanical properties, so your finger may not slide so easily on the surface.
As one of its basic components, touchscreens have sensors that are based on electrical currents. The sensors are designed so that when you touch the screen with your fingers, a circuit is created directly at the contact point. This allows the phone to record where it touches the screen and use it as part of its user interface. The materials that make up the screen and its coating are intact for optimal operation. It is better to follow the manufacturer's instructions and do not use alcohol or bleach to clean the screen of your phone.
Q : How would you recommend cleaning your phone without damaging the device?
A : There are a number of online manuals that provide recommendations on how to best disinfect a touchscreen device using milder methods than alcohol or bleach. Most are the dilution of alcohol with water, a substance that the engineers who developed the touch screens would be more likely to come into contact with (both from contact with human fingerprints and from accidental exposure), and therefore, therefore we have optimized the device so that it is stable under these conditions. When diluted appropriately, alcohol can have some of its disinfectant properties.
Q : Could phone covers and screens be designed to be easier to withstand cleaning? Do you think it would be possible to develop an antimicrobial coating that prevents germs or pathogens from sticking to the surface of a touchscreen?
A : It is certainly a possibility and probably an active area of research. The challenge is that the materials and structures that make up these devices have to perform many functions: they have to be transparent so that you can see the screen, they have to be resistant to electricity when they are not touched and when the conductors They must be mechanically strong so that they do not break. They must be easy to clean with simple cleaning and, above all, be able to withstand stains.
There is already an abundance of material properties used in these devices and any additional properties require reformulation of the materials, not to mention a review of the manufacturing and processing conditions. With any reformulation it is possible that material components added to impart a new property will adversely affect some of the other material properties that are critical to the operation of the device. As more components are added to a material's required specifications, developing the right structure becomes exponentially more difficult. While these types of coatings are certainly something for consumers and businesses, it is a difficult task to further improve the performance of these materials through many different design criteria.
The oleophobic coatings already used cannot be cleaned completely and probably already prevent microbial adhesion, at least to a limited extent. However, they do not completely rule out the possibility of contamination, which we are now thinking much more about in view of the current pandemic.
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