There are two main types of smoke alarm tech, says Raman Chagger, principal consultant at BRE, the Building Research Establishment. Ionisation-based systems use a tiny amount of radioactive material to charge, or ionise, particles in the air which flow between two small plates. Should smoke interrupt that flow of charged particles, the alarm goes off.
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Today's actuators, even the state-of-the-art ones, are still largely made from metals, hard plastics and electronics. But there are other ideas around. Tolley and his colleagues have been working on a very different approach.