An automated miniaturized creatinine sensing system

In this paper we report on the recently demonstrated, quartz resonator based thermal biosensor configured as a biomedical instrumentation system for continuous monitoring of kidney function based on the measurement of urinary creatinine excretion. The biosensor consists of a reaction chamber which is physically separated but located in close proximity to a micromachined quartz resonator-based temperature sensor. The highly effective coupling of heat from the reaction chamber to the quartz resonator due to close proximity (10-50 microns) and the extremely high absorption coefficient of quartz in the 8-12 μm wavelength range renders this system into a very sensitive thermal sensor design. The non-contact measurement results in no confounding mass loading effects on the quartz resonator and therefore provides clear calorimetric data. The sensor uses creatinine iminohydrolase enzyme immobilized on polystyrene films designed for disposable use. We have successfully integrated the sensor with a programmable miniaturized fluidic system from LabSmith^® Inc. to form a miniaturized test system. In this paper we present the latest results on noncontact thermal sensor configuration integrated with miniature automated fluidic system that is capable of continuous monitoring of kidney function based on the measurement of urinary creatinine excretion.