Materials science and the sensor revolution

The analytical method can be defined as the sequence of events that must take place in order to obtain a reliable measurement. Clearly there are many potentially limiting factors in any WSN deployment, including power management, communications strategy, and incorporation of a degree of local self-diagnostics or intelligence at the so-called sensing node. But these issues are common to all WSN deployments, and as scaled-up deployments based on physical transducers are now happening, they are not the limiting factor inhibiting equivalent deployments of bio/chemosensors. The core challenge for these devices, as mentioned above, is the ability to provide reliable data over extended periods of deployments (ideally years). So why after decades of research, and huge investments, are we still confounded by this challenge? The answer lies in failure of the integrity of the analytical method over time(5). In environmental water quality monitoring, the active sensing surfaces of bio/chemo-sensors that are directly exposed to the sample, change with time, due primarily to biofouling, which causes the response characteristics (sensitivity, baseline, selectivity etc.) to change unpredictably, leading rapidly to device failure(6).