A design of a microwave noninvasive continuous blood glucose monitoring sensor and its interference test results are presented. The novelty of the proposed sensor is that it comprises two spatially separated split-ring resonators, where one interacts with the change in glucose level of a sample under test while the other ring is used as a reference. The reference ring has a slightly different resonant frequency and is desensitized to the sample owing to its location, thus allowing changes in temperature to be calibrated out. From an oral glucose tolerance test with two additional commercially available sensors (blood strip and continuous glucose monitor) in parallel, we obtained encouraging performance for our sensor comparable with those of the commercial sensors. The effects of endogenous interferents common to all subjects, i.e., common sugars, vitamins (ascorbic acid), and metabolites (uric acid) have also been investigated by using a large Franz cell assembly. From the interference test, it is shown that the change in sensor response is dominated by changes in glucose level for concentrations relevant to blood, and the effects of interferents are negligible in comparison.

In this paper, we discuss the potential of using microwave techniques in the refinement of heavy fraction of petroleums such as bunker oil. After discussing the fundamental issues associated with conversion of microwave energy into heat, we present measurements of the dielectric properties of heavy oils at 2.45 GHz using a highly sensitive resonant cavity method, and also over a broader frequency range (100 MHz to 8 GHz) using a coaxial probe technique. We find that the dielectric loss is very small even in these heavy oils, but still may be sufficiently large to provide efficient conversion of microwave energy into heat on untreated samples, and could be massively enhanced by means of a microwave-absorbing additive (e.g., carbon black). We conclude by discussing the design of a suitable microwave actuator for heavy oil cracking within a flow process.

In this paper, a microwave non-invasive blood glucose monitoring system operating at around 1.4 GHz is designed and its performance in terms of accuracy and repeatability is evaluated by a clinical trial involving 24 human subjects, with and without diabetes. Direct comparison with the most accurate benchtop glucose analyzer shows the exceptional accuracy and repeatability of the proposed system.

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Previously reported clinical performances of microwave noninvasive blood glucose monitoring sensor look promising. It is clear that dielectric properties are changing when the food intake takes place, but the exact physiological mechanism is not clear. In an attempt to figure out the physiological mechanism of microwave noninvasive blood glucose monitoring sensor, this paper presents a series of studies to find out a) the penetration depth of the microwave resonator-based sensor and b) the effect of permittivity variation of human tissues on the microwave resonator parameters.