Method and apparatus for monitoring the ingestion of food and/or drink by a subject
There is provided an apparatus for monitoring the ingestion of food and/or drink by a subject, the apparatus comprising a control unit that comprises a first obtaining module configured to obtain measurements of one or more physiological characteristics of the subject; a second obtaining module configured to obtain measurements of eddy currents generated in the body of the subject by an externally-applied magnetic field; a setting module configured to set a respective cut-off frequency for one or more filtering stages based on a respective frequency for each of said one or more physiological characteristics; a filtering module configured to filter the measurements of eddy currents using the one or more filtering stages to remove signal components due to the one or more physiological characteristics; and a processing module configured to process the filtered measurements to determine whether food and/or drink is present in the stomach of the subject.
1. An apparatus for monitoring the ingestion of food and/or drink by a subject, the apparatus comprising:
a control unit that comprises:
a first obtaining module configured to obtain measurements of one or more physiological characteristics of the subject;
a second obtaining module configured to obtain measurements of eddy currents generated in the body of the subject by an externally-applied magnetic field;
a setting module configured to set a respective cut-off frequency for one or more filtering stages based on a respective frequency for each of said one or more physiological characteristics;
a filtering module configured to filter the measurements of eddy currents using the one or more filtering stages to remove signal components due to the one or more physiological characteristics; and
a processing module configured to process the filtered measurements to determine whether food and/or drink is present in the stomach of the subject.
2. An apparatus as claimed in claim 1 , wherein the one or more physiological characteristics comprises one or more of heart rate and breathing rate.
3. An apparatus as claimed in claim 1 , wherein the processing module is configured to process the filtered measurements to determine whether food and/or drink is present in the stomach of the subject by:
comparing the amplitude of the filtered measurements at a time instant to a threshold.
4. An apparatus as claimed in claim 3 , wherein the processing module is further configured to process the filtered measurements to determine whether food and/or drink is present in the stomach of the subject by:
determining that food and/or drink is present in the stomach if the amplitude at the time instant is above the threshold.
5. An apparatus as claimed in claim 3 , wherein the processing module is further configured to process the filtered measurements to determine whether food and/or drink is present in the stomach of the subject by:
processing the filtered measurements to identify a signal relating to peristalsis in the subject; and
determining that food and/or drink is present in the stomach of the subject if the amplitude at the time instant is above the threshold and the signal relating to peristalsis indicates that peristalsis is occurring in the subject.
6. An apparatus as claimed in claim 1 , wherein the processing module is configured to process the filtered measurements to determine whether food and/or drink is present in the stomach of the subject by:
determining an amount by which the amplitude of the filtered measurements has changed over a predetermined time window; and
comparing the amount by which the amplitude of the filtered measurements has changed over the predetermined time window to a threshold.
7. An apparatus as claimed in claim 6 , wherein the processing module is further configured to process the filtered measurements to determine whether food and/or drink is present in the stomach of the subject by:
determining that food and/or drink is present in the stomach if the amount is above the threshold.
8. An apparatus as claimed in claim 6 , wherein the processing module is further configured to process the filtered measurements to determine whether food and/or drink is present in the stomach of the subject by:
processing the filtered measurements to identify a signal relating to peristalsis in the subject; and
determining that food and/or drink is present in the stomach of the subject if the amount is above the threshold and the signal relating to peristalsis indicates that peristalsis is occurring in the subject.
9. An apparatus as claimed in claim 1 , wherein the apparatus further comprises:
an excitation coil for generating an eddy current in the subject; and
a measurement coil for measuring the eddy current in the subject.
10. An apparatus as claimed in claim 1 , wherein the apparatus further comprises:
one or more physiological characteristic sensors for obtaining the measurements of the one or more physiological characteristics of the subject.