Small form factor digitally tunable NMR in vivo biometric monitor for metabolic state of a sample

A nuclear magnetic resonance (NMR) monitoring device, comprising:

• at least one magnet configured to generate a primary magnetic field;
• a transceiver coil arranged within the primary magnetic field, wherein the transceiver coil is configured to apply a time series of radiofrequency (RF) pulses to a sample located within the primary magnetic field and to detect an NMR signal generated in response to application of the time series of RF pulses;
• a tuning circuit coupled to the transceiver coil, wherein the tuning circuit automatically adjusts a resonant frequency of the transceiver coil to a frequency associated with the primary magnetic field based on a dynamically determined transmitted signal, wherein the dynamically determined transmitted signal is different from the time series of RF pulses;
• and
• an NMR spectrometer having a software defined radio (SDR) architecture, wherein the NMR spectrometer is communicatively coupled to the transceiver coil, wherein the NMR spectrometer comprises:
• digital pulse generation circuitry configured to generate a digital representation of the time series of RF pulses;
• a digital-to-analog converter configured to convert the digital representation of the time series of RF pulses to an analog signal provided to the transceiver coil;
• an analog-to-digital converter configured to convert the detected NMR signal to a digital signal;
• and
• digital receive circuitry configured to process the digital signal to determine at least one metabolic state of the sample;
• at least one field sensor configured to measure at least one property of the primary magnetic field;
• at least one microcontroller unit configured to determine the frequency associated with the primary magnetic field based, at least in part, on the at least one measured property of the primary magnetic field and stored values;
• and
• wherein the tuning circuit comprises at least one digitally-tunable component arranged in series with the transceiver coil, and wherein the microcontroller unit is further configured to adjust a value of the at least one digitally-tunable component based, at least in part, on the determined frequency associated with the primary magnetic field.