Device for non-invasive substance detection

A device for transdermally detecting the concentration of one or more substances in a subject's bloodstream, the device comprising:

• a signal generation module arranged to generate microwave frequency signals at one or more discrete frequencies;
• a sensor module comprising at least one microwave resonance sensor arranged to make contact with a subject's skin, the at least one microwave resonance sensor arranged to transmit microwave frequency signals generated by the signal generation module into the subject's body;
• and
• a signal processing module connected to the at least one microwave resonance sensor and arranged to:
• detect a first resonance characteristic and a second resonance characteristic of the at least one microwave resonance sensor, and
• process the first resonance characteristic to determine whether said first resonance characteristic satisfies a first predetermined criteria and process the second resonance characteristic to determine whether said second resonance characteristic satisfies a second predetermined criteria in order to determine the concentration of one or more substances in a subject's bloodstream, wherein the first resonance characteristic is a first amplitude response associated with a microwave frequency signal at a first discrete frequency, and the second resonance characteristic is a second amplitude response associated with a microwave frequency signal at a second discrete frequency,
• wherein the signal processing module is adapted to process the first and second resonance characteristics to determine the concentration of one or more substances in a subject's bloodstream by inputting the first and second resonance characteristics into a neural network that is trained to identify a concentration of a substance in a subject's bloodstream.