APPARATUS AND METHOD FOR RADIO FREQUENCY SPECTROSCOPY USING SPECTRAL ANALYSIS

A source of high frequency electromagnetic radiation is coupled to a specimen containing a target chemical whose presence and/or concentration is to be ascertained. Preferably the source radiation includes a plurality of high frequency spectra, at least one of which encourages energy transfer with the chemical of interest. The source radiation is coupled to the specimen via a probe pair that is also used to access a return signal representing an interaction between the source signal and the specimen. The return signal is processed to yield a spectral signature correlating to the target chemical and/or its concentration. Preferably signal processing compares frequency spectra within the source signal to spectra within a sampled return signal. The sampled return signal is a signal obtained by sampling a return signal at the probe pair and by sampling the response to the source signal of a circuit that electrically approximates the specimen. The amplitude and/or phase difference between the sampled return signal and the source signal provides recognition of the spectral signature. Target chemical concentration data may be obtained from the signature and can be displayed in a number of ways. Operation of the signal processor may be optimized using a neural network. In the preferred embodiment, the specimen is a human finger that is pressed against the probe pair, and the chemical is glucose. The invention thus permits a lay user to non-invasively determine his or her glucose level.