Cornell University researchers have built a device that can detect a single DNA molecule.

The device can be combined with microfluidics to perform genetic analysis of very small samples of DNA, even the amount present in a single cell. Current techniques for genetic analysis require small samples of DNA to be replicated many times through PCR amplification.

The researchers believe their technology could be used to identify even smaller organic molecules, including proteins, and could have widespread applications in medical and forensic diagnosis.

The device uses arrays of cantilever oscillators 3 to 5 microns long and 90 nanometers thick on silicon chips. When excited by energy from a laser, these cantilevers oscillate at frequencies of around 11 to 12 MHz. The frequency is measured by shining another laser on the oscillator and noting interference patterns in the beam caused by the reflected light.

In the reported experiments, the change in mass of 1 attogram was enough to shift the frequency of vibration by 50 Hz or more, depending on the size of the oscillator.