Oct 08, 2018 19:00:00

A special filter called contradictory common sense 'Can pass only large objects' will be developed

Everyone knows that a vacuum cleaner, an air conditioner filter, a coffee filter, etc. have the task of "damming a large object and allowing only small items" to pass. On the contrary, however, a mysterious filter of "passing only big things" has been developed. As applications, it seems that "Filter that can not pass only fly" or "Deodorant filter of toilet" etc.

Free-standing liquid membranes as unusual particle separators | Science Advances
http://advances.sciencemag.org/content/4/8/eaat3276

This improbable membrane can trap flies in a jar - and odor in a toilet | Science | AAAS
http://www.sciencemag.org/news/2018/08/improbable-membrane-can-trap-flies-jar-and-odor-toilet

A research team by scientists at the State University of Pennsylvania who developed a "true reverse filter" that completely turns over the concept of filter by 180 degrees. The usual filter was changing the size of the object that can pass by changing the size of the small gap opened on the surface. On the other hand, the filter developed by the research team made it possible to pass only objects with a certain size and kinetic energy by using the "surface tension" of the liquid.

You can see the fact that the filter is functioning in the following movie.

This improbable membrane can trap flies in a jar - and odor in a toilet - YouTube

The filter of coffee does not pass large particle coffee beans, and it passes only coffee extracted water (hot water) so that it can drink transparent coffee.

Meanwhile, the research team at Pennsylvania State University developed a special filter called "just let big things pass" the opposite of the coffee filter.

The basis for the new idea was the appearance of Phagocytosis ( phagocytosis ) in which cells in the human body take only objects of a certain size such as bacteria and viruses into the cell.

What is needed to make this special filter is ring sodium and nonionized water, and sodium lauryl sulfate (SDS) used as a material for foaming agents and detergents.

The principle that this filter works is to make use of the difference in the kinetic energy of the object. Objects dropped from a certain height will have kinetic energy due to falling. At this time, large and heavy objects will have greater kinetic energy and can overcome the surface tension of the liquid and pass through the liquid film. And, after the object has passed through the membrane, the hole opened by the passage of the object is automatically closed by the high surface tension of the liquid.

There are more features of this filter. It is made of liquid with high surface tension, so it is very durable. At the experimental stage, we conducted a test to keep foreign substances repeatedly applied to the filter and found that the function of the filter was not impaired at all even after 3 hours.

It is expected that a filter which has never existed will be born. For example, by allowing solid waste to pass through while preventing gaseous gas from passing through, a completely new toilet deodorizing device is born ......