Nanotechnology in environmental sensors

For chemical and biological sensors that are needed in environmental research, nanomaterials and nanofabricated devices offer improvements in existing sensor designs and also entirely new sensor types. Outstanding problems in the area of autonomous chemical and biological sensors (nano or not) are the lack of refreshable surfaces that can recover from chemical binding, the need to minimize power consumption, and the need to respond to rare molecules at low concentrations without access to complex lab-based amplification techniques. Nanoparticle-enabled techniques that use disposable reagents (litmus papers, colorimetric assays) may produce excellent new laboratory methods for environmental research, while nanowire or nanocantilever sensors hold advantages for unattended operation. Keeping sensors free from environmental fouling is also an outstanding issue. Here, other nanoscale phenomena such as superhydrophobicity may come in handy to prevent binding of interfering species. Nanomaterials' small thermal mass, high chemical reactivity, dimensions comparable to analytes of interest, and enormous specific surface area provide significant practical advantages over conventional sensor systems. The areas where nanomaterial-enabled sensors particularly promise to outperform conventional sensors are in low-power operation, sensitivity, and response speed.