A breakthrough on two levels
Initially, the researchers only coated the tips of the CNTs with gold. The first experiments with the BPE test molecule showed them that they were on the right track, but that the detection limit could not be reduced to quite the degree they had hoped. Eventually, they discovered that the electrons required on the gold layer surface for generating what is referred to as plasmon resonance were flowing out via the conductive carbon nanotubes. The task was then to figure out how to prevent this plasmonic energy leakage.
The researchers coated the CNTs with hafnium oxide, an insulating material, before applying a layer of gold. "This was the breakthrough," says Altun. The insulation layer increased the sensitivity of its sensor substrate by a factor of 100,000 in the molar concentration unit.
"For us as scientists, this was a moment of triumph," agrees Park, "and it showed us that we had made the right hypothesis and a rational design."
The key to the successful development of the sensor was therefore twofold: on the one hand, it was their decision to continue using CNTs, whose morphology is essential for maximising the number of 'hot spots', and on the other hand, it was the fact that these nanotubes were double-coated.
Park and Bond would now like to go one step further and bring their new principle to market, but they are still seeking an industry partner. Next, they want to continue improving the sensitivity of the sensor, and they are also looking for potential areas of application. Park envisions installation of the technology in portable devices, for example to facilitate on-site analysis of chemical impurities such as environmental pollutants or pharmaceutical residues in water. He stresses that invention of a new device is not necessary; it is
|Contact: Hyung Gyu Park|