turning from green to red when the air runs low. The device can take in enough air for two minutes of diving and takes approximately the same amount of time to be refilled. “When you put the compressor into the unit with all of the rest of the stuff, the batteries and the electronics and the membranes for the scuba delivery, the big trick was to be able to get it small enough so that it would be able to be held through the teeth and out of the mouth,” Redmond says. The electrics are shielded from the water in the casing and are recharged using inductive power transfer – a system using an electromagnetic field, similar to the pads which can wirelessly charge mobile phones, so that there is no need for exposed wires. Redmond says the mouthpiece feels similar to using a snorkel. He likens it to an extension of the lungs in that the user is taking a deep breath and then using it underwater. “It is an extension of the body’s capacity to store air,” he says. The prototype, made from high-density foam, aluminium and silicone, has been tested in parts. Redmond says he has shown that the motor can compress two minutes’ worth of air into the unit and that the design can be effectively held in the diver’s mouth. What he has not yet done is test the device on a diver, fully submerged for two minutes. But, with enough testing, Redmond is confident he can get a fully