# US 11,076,788 B2 · Method and apparatus for deriving a mental state of a subject

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- Number: US 11,076,788 B2
- Document ID: US11076788B2
- Status: Granted
- Kind: B2
- Application number: 15/537,967
- Filed: 2015-12-23
- Published: 2017-11-30
- Granted: 2021-08-03
- Earliest claimed: 2014-12-30
- Assignees: Nitto Denko Corporation
- Applicants: Nitto Denko Corporation
- Inventors: Aye Aung; Kittipong Kasamsook; Visit Thaveeprungsriporn; Pimporn Muaynoi
- Web page: https://patentgrep.com/patent/US11076788B2

## CPC

- A61B 5/165: {Evaluating the state of mind, e.g. depression, anxiety}
- A61B 5/0205: Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
- A61B 5/021: Measuring pressure in heart or blood vessels
- A61B 5/024: Measuring pulse rate or heart rate
- A61B 5/02405: {Determining heart rate variability}
- A61B 5/0816: {Measuring devices for examining respiratory frequency (measuring frequency of electric signals G01R23/00)}
- A61B 5/1118: {Determining activity level}
- A61B 5/16: Devices for psychotechnics (using teaching or educational appliances G09B1/00 - G09B7/00); Testing reaction times {; Devices for evaluating the psychological state}
- A61B 5/7235: {Details of waveform analysis (detecting specific parameters of the electrocardiograph cycle A61B5/349)}
- A61B 5/7239: {using differentiation including higher order derivatives}
- A61B 5/7264: {Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems}
- A61B 5/7275: {Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor}
- A61B 5/741: {using synthesised speech}
- A61B 5/743: {Displaying an image simultaneously with additional graphical information, e.g. symbols, charts, function plots}
- A61B 5/7465: {Arrangements for interactive communication between patient and care services, e.g. by using a telephone network (telemetry of measured physiological signal A61B5/0002)}
- G16H 10/60: for patient-specific data, e.g. for electronic patient records
- G16H 20/70: relating to mental therapies, e.g. psychological therapy or autogenous training
- G16H 40/67: for remote operation
- A61B 5/0002: {Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network (endoradiosondes A61B5/07)}
- A61B 5/14507: {specially adapted for measuring characteristics of body fluids other than blood (devices for taking samples of body liquids A61B10/0045)}
- A61B 2560/0271: using a remote monitoring unit
- A61M 2021/0027: {by the hearing sense}
- A61M 2021/005: {images, e.g. video}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- G16H: HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA
- A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)}

## Abstract

A method (1500) for deriving a mental state of a subject is disclosed. The method comprises receiving (1502) a bio-signal from the subject; calculating respective statistical variations of at least two physiological parameters derived from the bio-signal; determining (1504) an arousal level of the subject based on the calculated statistical variations of the at least two physiological parameters; deriving a time-domain heart rate variability signal from the bio-signal for calculating at least two heart rate variability parameters; determining (1506) a valence level of the subject based on the at least two heart rate variability parameters; and deriving (1508) the mental state from the arousal level and valence level. A related apparatus is also disclosed.

## Claims

### Claim 1

A method for determining an arousal level of a subject, the method comprising:
(i) receiving a bio-signal from a wearable device worn by the subject, the bio-signal including at least one selected physiological parameter, the at least one selected physiological parameter including pulse pressure;
(ii) segmenting the bio-signal into a plurality of processing windows, each processing window having a time duration that is adaptively configured depending on the at least one selected physiological parameter to include at least five consecutive cardiac cycles of the bio-signal;
(iii) calculating statistical variation of the at least one selected physiological parameter including pulse pressure derived from the at least five consecutive cardiac signals of the bio-signal;
(iv) determining the arousal level of the subject based on the calculated statistical variation of the at least one selected physiological parameter including pulse pressure, wherein the arousal level is determined to be in a stress level if the calculated statistical variation of the pulse pressure is greater than a threshold value, in which the threshold value is within a range of about 3.0-12.0 mmHg mercury level, and
(v) outputting the arousal level and, based on the determined arousal level, a training or an intervention to assist with managing the stress level.

### Claim 2 (depends on 1)

The method of claim 1, wherein the at least five cardiac cycle includes time intervals relating to a systolic peak, start time and end time of each cardiac cycle.

### Claim 3 (depends on 1)

The method of claim 1, wherein calculating the statistical variation of the at least one selected physiological parameter including pulse pressure includes calculating a standard deviation of the pulse pressure.

### Claim 4 (depends on 3)

The method of claim 3, wherein the arousal level is determined to be in the stress level if the calculated standard deviation of the pulse pressure is greater than the threshold value, in which the threshold value is within a range of about 6.0-10.0 mmHg mercury level.

### Claim 5 (depends on 1)

The method of claim 1, wherein the at least one physiological selected parameter comprises first and second physiological parameters derived from the bio-signal, wherein one of the first and second physiological parameters is the pulse pressure, and the other of the first and second physiological parameters is selected from the group consisting of respiration rate and heart rate.

### Claim 6 (depends on 1)

A computer program stored in a storage medium of a wearable device, the computer program having a set of instructions, when executed, is arranged to control a processor of the wearable device to perform the method of claim 1.

### Claim 7 (depends on 1)

A wearable device for determining an arousal level of a subject, the wearable device including a processor configured to perform the method of claim 1.

### Claim 8

A method for deriving a mental state of a subject, the method comprising:
(i) receiving a bio-signal from a wearable device worn by the subject, the bio-signal including at least two selected physiological parameters, one of which includes pulse pressure;
(ii) segmenting the bio-signal into a plurality of processing windows, each processing window having a time duration that is adaptively configured depending on the at least two selected physiological parameters to include at least five consecutive cardiac cycles of the bio-signal;
(iii) calculating respective statistical variations of the at least two selected physiological parameters derived from the at least five consecutive cardiac cycles of the bio-signal;
(iv) determining an arousal level of the subject based on the calculated statistical variations of the at least two selected physiological parameters, and
(v) outputting the arousal level and, based on the determined arousal level, a training or an intervention to assist with managing the arousal level.

### Claim 9 (depends on 8)

A method of claim 8, wherein the at least two selected physiological parameters further include one of respiration rate and heart rate.

### Claim 10 (depends on 8)

A wearable device for deriving a mental state of a subject, the wearable device including a processor configured to perform the method of claim 8.