Whether they are detecting toxic molecules in the air or pathogenic bacteria in a vat of yoghurt, many microscopic sensors share a crucial weakness: the ultra-thin wires that relay signals from the physical sensing components to the circuitry. If those fragile wires break or corrode, the sensor becomes useless. Nanometer Nanotechnology

Now a wireless sensor has been developed that detects substances through their effect on an applied magnetic field. "This is a wireless technology you can embed in any environment where sub-millimetre wiring is a risk, either due to spark risk or because of its fragility," says the sensor's developer, Mike Gibbs, an expert in engineering Materials at the University of Sheffield in the UK.

Typical molecular sensors, for example, use 1-micrometre-long silicon cantilevers that ping up and down like a diving board when the target molecule lands on them. This vibrates a piezoelectric crystal, producing a fluctuating current of the same ...