IN SITU, REMOTELY INTERROGATABLE MAGNETOCHEMICAL SENSORS

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DESCRIPTION: (Adapted from the investigator's abstract) This proposal seeks funding for the development of a new type of sensor that offers the opportunity for remote, in-situ, continuous, long term monitoring of given chemical stimuli. In its initial design the sensor is comprised of a thing polymeric layer made so that it swells in the presence of certain stimuli, bounded on each side by a magnetically soft thin film. For fixed magnetic layer design, the magnetic switching characteristics of the sensor 'sandwich' are a function of the thickness of the intervening polymeric spacer layer. Placed within a sinusoidal magnetic field the magnetization vector of the sensor periodically reverses directions, generating a series of voltage spikes in suitably located detecting coils. The general shape and magnitude of the voltage spikes are dependent upon how much the spacer layer has swollen or contracted in response to the given stimuli. Since the sensor is monitored through changes in magnetic flux, no physical connections such as wires or cables are needed to obtain sensor information, nor line of sight as needed with laser telemetry; the sensors can be placed within opaque or metallic enclosures such as people, hermetically sealed bags, etc. The polymeric chemistry is flexible and selective. The polymer swelling is due only to the functional group, it does not involve the polymer backbone. Therefore, the sensor will respond only to the given chemical analyte for which it has been designed. While the sensors are quite durable, the projected cost of the sensors is inexpensive enough to be readily used on a disposable basis. One detecting unit can serve an unlimited number of sensors; the technology would be ideally suited for monitoring contamination of blood supplies or foodstuffs through sensing for CO2 levels, in-vivo glucose or pH levels, moisture levels in sealed containers, metal ion pollutants in water pipes, etc. The primary research objectives of this proposed work are: (1) Precisely determine the variation in voltage with pH for the pH sensor and how it is affected by the thickness of the polymer and magnetic layers, and polymer formulation variables. (2) Develop technology for controlling sensor response times. (3) Refine sensor detection electronics. (4) Develop polymers or other space layer materials for applications including glucose, CO2, hydrogen sulfide and hydrazine. (3) Evaluate the robustness of the different polymer layers. (6) Translate developmental work to field demonstration units to promote application of the new sensor technology.