Biocompatible Flow Sensor with Integrated Solvent Concentration Measurement

We report on the concept and development of two micro sensors for application in an intraoral drug delivery system (DDS) that has the size of two molar teeth. The micro sensors add intelligence to the DDS: a flow sensor measuring the mass flow of the drug solution and a concentration sensor detecting when the drug pill inside the DDS is going to be exhausted. Both sensors are monolithically integrated on one sensor chip having dimensions of 5×3×1 mm
³
. The flow sensor is optimized for a measuring range of 50 mμ/h. The concentration sensor is able to measure concentrations which are around the solubility limit of the used drug substance. The sensor we report here provides the opportunity to dynamically measure the concentration in the close vicinity of the location where the mass flow is measured. Thus, the combined sensor is not only able to measure the flux of the drug solution but is also able to determine the flux of a dissolved substance at any time.