For my switch that doesn’t use hands, I come up with the idea to make use of electrolyte solution as the conductor in the switch. The reason for that is because it is each to move liquid from one place to another inside my switch by simply blowing them.

First, I construct a simple open circuit as drawn in the diagram — an Arduino unit connected to the USE port on my laptop as the power source, an LED, a resistor, wires connecting them and two open end wires to be connected to my switch.

The electrolyte I choose to use for my switch is the one with the most accessibility — salt (NaCl). I put some salt that I take from D2 into a can with water and shake it well to help the dissolution.I want to build a device that’s open on both end and easy for me toblow from one end. And I use some straws to build such a device.First, I insert one long straw into one short straw. The long straw is for the excess salt water to be held and the short straw is for a “blowing straw” to be inserted. I put a certain amount of salt water into the device that has the height of the diameter of the straws (which doesn’t go up to the vertical part of the device).Next, I insert the two dangling wires into the two open ends of the device. I want the default state of my switch to be breaking the connection so I put the wire in the long straw slightly higher than the surface of the solution. The last step of building is to add a short “blowing straw” onto the short straw to make blowing easier.

To turn on the switch, gently blow from the “blowing straw” to make the two wires both in contact with the salt water.

The default state (broken connection) can be changed to connection simply by adjusting the position of the wire inside the long straw(make it in contact with the salt water). In this case, the connection can be broken by blowing harder to make the other wire no longer in contact with salt water.