# Battery powered trousers could have you walking on walls

A student paper has concluded that battery-powered trousers allowing people to walk on vertical surfaces are feasible (Image: University of Leicester).

A group of students at the University of Leicester in the UK have shown that it is theoretically possible to build a pair of battery-powered trousers which would allow the wearer to walk on walls or even the ceiling, if only for a short time.

In the 1993 Wallace & Gromit claymation movie The Wrong Trousers, Wallace buys Gromit a pair of battery-powered robotic trousers that, among other things, allow the wearer to walk up vertical walls or even on the ceiling. They work both on Earth and in space using a combination of vacuum and magnetic field generators placed in the soles of the boots. A team of graduate students at the University of Leicester set out to establish whether building such a gadget is physically possible.

The mechanics of walking means that the device needs to function even when only a single boot is in contact with the wall or ceiling. Therefore, the students made their calculations assuming that only one boot is supporting the entire weight of both the person and the device itself.

If each boot had a slightly raised rubber insulator on the edge of its sole, this would create a cavity when the wearer puts their foot down on a surface. Applying a vacuum to this cavity would make the boot stick firmly to the surface, similarly to a suction cup, but with finer control.

Making basic assumptions on the area of the sole as well as the weight of the wearer and the device itself, the students concluded that the vacuum generator would need to reduce the pressure of the air underneath the boot by approximately 18.5 kPa compared to the surrounding environment. This is roughly the vacuum created by an ordinary vacuum cleaner.

According to the students, the main issue with building such trousers wouldn't be generating enough vacuum, but rather powering them effectively. Because of weight constraints, the students say their gravity-defying pants could realistically only be powered from a battery for about 20 minutes before needing recharging. The alternative would be to draw power directly from the grid, though this would obviously constrain movement.

Because the device relies on creating a lower pressure than the surrounding environment, the trousers wouldn't work in space, where pressure is already close to a perfect vacuum (negative pressures are possible in liquids, which is how very tall trees can carry water all the way up to their leaves, but gases cannot have negative pressure). The students say that a possible workaround could be to use magnetic generators rather than vacuum generators.

The students presented their findings in a paper for the Journal of Physics Special Topics, a peer-reviewed student journal designed to give students practical experience of writing, editing, publishing and reviewing scientific papers.

Source: University of Leicester

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