A REMOTELY INTERROGATABLE MAGNETOCHEMICAL PH SENSOR

A new type of sensor is presented that allows for remote, in-situ, con tinuous, long term monitoring of given chemical stimuli. The sensor is comprised of a thin polymeric layer made so that it swells in the pre sence of certain stimuli, bounded on each side by a magnetically soft thin film, The magnetic switching characteristics of the sensor are de pendent upon the thickness of the intervening polymeric spacer layer, Placed within a sinusoidal magnetic field the sensor generates a serie s of voltage spikes in suitably located detecting coils, The magnitude of the voltage spikes are dependent upon how much the spacer layer ha s swollen in response to the given stimuli, The polymeric chemistry is very flexible, and can be made to selectively swell in response to, f or example, moisture, pH, ion concentration, or atmospheric CO2, The s ensor principle has been demonstrated using lightly crosslinked poly ( dimethylamino)-ethylmethacrylate to detect pH.