Monitoring device

1 . A monitoring system, comprising:

a sensing module comprising an enclosure, the enclosure housing an electronics sub-assembly comprising a first sensor assembly and a second sensor assembly; and

one or more processors and computer-readable media having stored thereon executable instructions that when executed by the one or more processors configure the sensing module to:

propagate, from the first sensor assembly, a sequence of light, the sequence of light comprising:

a first wavelength of light for a first predetermined amount of time,

after the first predetermined amount of time, propagate no light for a second predetermined amount of time,

after the second predetermined amount of time, propagate a second wavelength of light for a third predetermined amount of time, and

substantially immediately after the propagation of the second wavelength of light, propagate a third wavelength of light for a fourth predetermined amount of time, wherein the first wavelength of light, the second wavelength of light, and the third wavelength of light all comprise different wavelengths of light,

detect, with the second sensor assembly, light propagated from the first sensor assembly,

calculate a value for the first wavelength by comparing a detected amount of the first wavelength of light detected by the second sensor assembly to a predetermined first amount of the first wavelength of light propagated from the first sensor assembly,

calculate a value for the third wavelength by comparing a detected amount of the third wavelength of light detected by the second sensor assembly to a predetermined second amount of the third wavelength of light propagated from the first sensor assembly,

calculate a difference between the value for the first wavelength of light and the value for the third wavelength of light,

when the difference is less than a threshold value, determine that the sensing module is not placed correctly, and

when the difference is equal to or greater than the threshold value, determine that the sensing module is placed correctly.

2 . The monitoring system of claim 1 , wherein the first wavelength of light ranges from 650 nm to 670 nm and the second wavelength of light ranges from 920 nm to 970 nm.

3 . The monitoring system of claim 1 , wherein the third wavelength of light is either in a light range of (i) 450 nm to 470 nm or (ii) 515 nm to 545 nm.

4 . The monitoring system of claim 1 , wherein the first sensor assembly comprises one or more light emitting diodes configured to propagate light to a target.

5 . The monitoring system of claim 1 , wherein the second sensor assembly comprises one or more photodiodes configured to measure an amount of light propagated from the first sensor assembly.

6 . The monitoring system of claim 1 , wherein the first sensor assembly comprises one or more light emitting diodes and one or more photodiodes.

7 . The monitoring system of claim 6 , further comprising a processor with executable instructions to compare the amount of light propagated from the first sensor assembly to the amount of light that is reflected off of a subject.

8 . The monitoring system of claim 6 , wherein the sensing module further comprises a heat flux sensor, and

the one or more processors and the executable instructions further configure the one or more processors to:

based on one or more readings from the heat flux sensor, determine that the sensing module is not placed correctly.

9 . The monitoring system of claim 6 , wherein the sensing module further comprises a temperature sensor.

10 . A method for determining proper placement of a monitoring device on a subject, comprising:

placing a monitoring device in contact with a skin of a subject, the monitoring device comprising a sensing module having an electronics sub-assembly with a first sensor assembly and a second sensor assembly;

propagating, from the first sensor assembly, a first wavelength of light for a first predetermined amount of time;

after the first predetermined amount of time, propagating, from the first sensor assembly, no light for a second predetermined amount of time;

after the second predetermined amount of time, propagating, from the first sensor assembly, a second wavelength of light for a third predetermined amount of time;

substantially immediately after the propagation of the second wavelength of light, propagating, from the first sensor assembly, a third wavelength of light for a fourth predetermined amount of time, wherein the first wavelength of light, the second wavelength of light, and the third wavelength of light all comprise different wavelengths of light;

detecting, with the second sensor assembly, light propagated from the first sensor assembly;

calculating a value for the first wavelength by comparing a detected amount of the first wavelength of light detected by the second sensor assembly to a predetermined first amount of the first wavelength of light propagated from the first sensor assembly;

calculating a value for the third wavelength by comparing a detected amount of the third wavelength of light detected by the second sensor assembly to a predetermined second amount of the third wavelength of light propagated from the first sensor assembly;

calculating a difference between the value for the first wavelength of light and the value for the third wavelength of light;

when the difference is less than a threshold value, determining that the sensing module is not placed correctly;

and when the difference is equal to or greater than the threshold value, determining that the sensing module is placed correctly.

11 . The method of claim 10 , wherein the first wavelength of light ranges from 450 nm to 470 nm and the second wavelength of light ranges from 920 nm to 970 nm.

12 . The method of claim 10 , wherein the first wavelength of light ranges from 650 nm to 680 nm and the second wavelength of light ranges from 515 nm to 545 nm.

13 . The method of claim 10 , wherein the first sensor assembly comprises one or more light emitting diodes configured to propagate light to a target.

14 . The method of claim 10 , wherein the second sensor assembly comprises one or more photodiodes configured to measure an amount of light propagated from the first sensor assembly.

15 . The method of claim 10 , wherein the first sensor assembly comprises one or more light emitting diodes and one or more photodiodes.

16 . The method of claim 15 , further comprising comparing the amount of light propagated from the first sensor assembly to the amount of light that is reflected off of a subject.

17 . The method of claim 15 , further comprising:

based on one or more readings from a heat flux sensor, determining that the sensing module is not placed correctly.

18 . The method of claim 10 , wherein the sensing module further comprises a temperature sensor.