System and method for determining poor sensor contact in a multi-sensor device

A system for determining sensor contact in a multi-sensor device, the system comprising:

• a first sensor having an output to supply measured photoplethysmography (PPG) signals;
• using a second sensor having an output to supply measured electrocardiogram (ECG) signals;
• a processor;
• a non-transitory memory;
• a sensor contact application residing in the non-transitory memory comprising a sequence of processor instructions, the sensor contact application receiving the PPG and ECG signals, detecting a correlation in time between PPG signals and corresponding ECG signals, and in response to the timing between correlated PPG and ECG signals remaining within a correlation deviation limit, determining a correlation state;
• wherein the sensor contact application detects the correlation in time as follows:
• measuring a plurality of subsequent PPG signals occurring no more than p milliseconds subsequent to a first ECG signal;
• removing from the plurality of PPG signals any PPG signals occurring subsequent to a second ECG signal, where the second ECG signal occurs subsequent to the first ECG signal;
• in response to the plurality of subsequent PPG signals having no members, determining that the correlation deviation limit associated with the first ECG signal has been exceeded;
• and,
• wherein the correlation state indicates a satisfactory quality of sensor contact with a user.

A system for determining sensor contact in a multi-sensor device, the system comprising:

• a first sensor having an output to supply measured photoplethysmography (PPG) signals;
• using a second sensor having an output to supply measured electrocardiogram (ECG) signals;
• a processor;
• a non-transitory memory;
• a sensor contact application residing in the non-transitory memory comprising a sequence of processor instructions, the sensor contact application receiving the PPG and ECG signals, detecting a correlation in time between PPG signals and corresponding ECG signals, and in response to the timing between correlated PPG and ECG signals remaining within a correlation deviation limit, determining a correlation state;
• wherein the sensor contact application compares a subsequent ECG signal level to an immediately previous detection threshold level, and in response to the subsequent ECG signal level exceeding the immediately previous detection threshold level by a factor of r, where r is a value greater than zero, determines a second missing sensor failure, and excludes all previously occurring ECG and PPG signals from subsequent correlation state determinations;
• and,
• wherein correlation state indicates a satisfactory quality of sensor contact with a user.