Methods and devices for aligning miniaturized spectrometers and impedance sensors in wearable devices

1. A device, comprising:

a flexible band designed to flex into a curvilinear shape, the flexible band comprising a shape, size, and flexibility designed for attaching the flexible band to a wrist of a user, wherein the wrist includes a dermal layer along a bottom half of the wrist and a muscular-walled tube within the wrist adjacent to the dermal layer along the bottom half of the wrist;

a user interface coupled to the flexible band and positioned on the flexible band to be situated, as the user wears the flexible band, adjacent to a top side of the wrist opposite the bottom half of the wrist;

a light source embedded in the flexible band, wherein the light source is positioned in the flexible band to emit light into the wrist through the dermal layer along the bottom half of the wrist as the user wears the flexible band;

a miniaturized spectrometer embedded in the flexible band and positioned in the flexible band at a distance along the band from the light source as defined by a curved non-linear light path between the light source and the miniaturized spectrometer, wherein the miniaturized spectrometer is configured to press against the bottom half of the wrist as the user wears the flexible band to receive the light through the dermal layer along the curved non-linear path;

an impedance sensor embedded in the flexible band and positioned in the flexible band to be situated, as the user wears the flexible band, against the bottom half of the wrist, wherein the impedance sensor comprises two or more rows of microelectrodes; and

a processing device coupled to the flexible band and communicatively coupled to the optical sensor and the impedance sensor; and

wherein the miniaturized spectrometer and the impedance sensor are positioned in the flexible band to simultaneously measure, as the user wears the flexible band, the feature of the muscular-walled tube or of the blood flowing through the muscular-walled tube.

2. The device of claim 1 , wherein the impedance sensor is positioned in the flexible band to be aligned approximately radially with the muscular-walled tube as the user wears the flexible band.

3. The device of claim 1 , wherein the light source and the miniaturized spectrometer are positioned in the flexible band to straddle the impedance sensor, the light source positioned along a first side of the impedance sensor, and the miniaturized spectrometer positioned along a second side of the impedance sensor opposite the first side of the impedance sensor.

4. The device of claim 1 , wherein the impedance sensor is positioned in the flexible band such that the two or more rows of microelectrodes are aligned in the flexible band to be approximately parallel to the muscular-walled tube or approximately perpendicular to the muscular-walled tube as the user wears the flexible band.

5. The device of claim 1 , wherein:

the light source is positioned in the flexible band to be situated along a first side of the muscular-walled tube against the dermal layer as the user wears the flexible band; and

the miniaturized spectrometer is positioned in the flexible band to be situated along a second side of the muscular-walled tube against the dermal layer as the user wears the flexible band.

6. The device of claim 1 , wherein:

the light source and the miniaturized spectrometer are positioned in the flexible band to straddle the muscular-walled tube as the user wears the flexible band, the light source positioned along a first side of the muscular-walled tube, and the miniaturized spectrometer positioned along a second side of the muscular-walled tube opposite the first side of the muscular-walled tube; and

the impedance sensor is positioned in the flexible band to be aligned approximately radially with a second muscular-walled tube as the user wears the flexible band, the second muscular-walled tube adjacent to the dermal layer along the bottom half of the wrist.

7. The device of claim 1 , wherein:

the processing device is configured to measure blood glucose simultaneously by the miniaturized spectrometer and the impedance sensor;

the impedance sensor and the miniaturized spectrometer or the light source are positioned in the flexible band adjacent to each other; and

the impedance sensor and the miniaturized spectrometer or the light source are positioned in the flexible band to be aligned approximately radially with the muscular-walled tube as the user wears the flexible band.

8. The device of claim 1 , wherein:

the processing device is configured to measure, by the impedance sensor, a hydration condition of the user;

the processing device is configured to measure, by the miniaturized spectrometer, a blood glucose level of the user; and

the processing device is configured to adjust a measurement of the blood glucose level of the user based on the hydration condition of the user, wherein a change in the hydration condition of the user skews the measurement of the blood glucose level.

9. The device of claim 1 , wherein the miniaturized spectrometer or the light source is positioned in the flexible band to be aligned approximately radially with the muscular-walled tube as the user wears the flexible band.

10. The device of claim 1 , wherein the impedance sensor is positioned in the flexible band to be aligned approximately radially with the muscular-walled tube as the user wears the flexible band.

11. A device, comprising:

a band configured to extend at least partially around a body part of a user, the body part comprising a dermal layer and a subdermal feature within body part;

a light source integrated into the band, wherein the light source is configured in the band to emit light into the body part through the dermal layer;

a miniaturized spectrometer integrated into the band and positioned in the band at a distance along the band from the light source as defined by a curved non-linear light path between the light source and the miniaturized spectrometer, wherein the miniaturized spectrometer is configured to press against the bottom half of the wrist as the user wears the flexible band to receive the light through the dermal layer along the curved non-linear path; and

an impedance sensor integrated into the band and configured to be positioned, as the user wears the band, against a same side of the body part as the miniaturized spectrometer, wherein the miniaturized spectrometer is configured in the band to be positioned along a same side of the body part as the impedance sensor as the user wears the band.

12. The device of claim 11 , further comprising a processing device configured to:

take, by the optical sensor, an optical measurement; and

take, by the impedance sensor, an impedance measurement simultaneously with the optical measurement.

13. The device of claim 12 , the processing device configured to:

correlate the impedance measurement and the optical measurement;

determine glucose measurement of the body part, the dermal layer, or the subdermal structure based on the correlation, wherein:

the optical measurement indicates a change in the glucose measurement, wherein the change in the glucose measurement is a combination of a change in glucose and a change in hydration in the body part, the dermal layer, or the subdermal structure; and

the impedance measurement indicates the change in the hydration in the body part, the dermal layer, or the subdermal structure; and

filter out the change in the hydration based on the impedance measurement from the glucose measurement to generate a glucose indicator.

14. The device of claim 11 , wherein the miniaturized spectrometer or the impedance sensor is positioned in the band at a distance along the band from the light source as defined by a curved non-linear light path between the light source and the miniaturized spectrometer.

15. The device of claim 11 , wherein:

the body part is approximately circular, approximately oval-shaped, or approximately elliptical;

the body part comprises a radius, the subdermal structure being aligned in the body part approximately along the radius; and

the miniaturized spectrometer or the impedance sensor is positioned in the band at a distance along the band from the light source as defined by a curved non-linear light path between the light source and the miniaturized spectrometer.

16. A method, comprising:

placing a wearable device at least partially around a body part of a user, the wearable device configured to take simultaneous measurements of a feature of the body part with two different types of sensors, the wearable device comprising:

a band shaped to extend at least partially around the body part of the user, the body part comprising a dermal layer, a subdermal structure within body part, a first side, and a second side facing a different direction than the first side;

a light source integrated into the band, wherein the light source is configured in the band to emit light into the body part through the dermal layer;

a miniaturized spectrometer integrated into the band and positioned in the band at a distance along the band from the light source as defined by a curved non-linear light path between the light source and the miniaturized spectrometer, wherein the miniaturized spectrometer is configured to press against the bottom half of the wrist as the user wears the flexible band to receive the light through the dermal layer along the curved non-linear path;

an impedance sensor integrated into the band and positioned in the band to be situated along a same side of the body part as the miniaturized spectrometer as the user wears the band, the same side comprising either the first side of the body part or the second side of the body part; and

a processing device configured to take simultaneous measurements with the miniaturized spectrometer and the impedance sensor, the processing device communicatively coupled to the impedance sensor and the optical sensor;

emitting, by the light source, the light through the body part;

detecting, by the optical sensor, the relevant constituent wavelength;

measuring an impedance of the body part by the impedance sensor simultaneously with the light source emitting the light and the optical sensor detecting the relevant constituent wavelength; and

communicating to the processing device an impedance measurement from the impedance sensor and an optical measurement from the optical sensor.

17. The method of claim 16 , further comprising comparing the impedance measurement and the optical measurement to determine a feature, a condition, or a constituent of the subdermal structure.

18. The method of claim 16 , further comprising determining, based on the impedance measurement or the optical measurement, an alignment of the wearable device on the body part relative to the subdermal structure.

19. The method of claim 16 ,

determining, by the processing device, a first condition of the body part based on the impedance measurement;

determining, by the processing device, a second condition of the body part based on the optical measurement;

comparing, by the processing device, the first condition of the body part with the second condition of the body part; and

determining whether the first condition and the second condition are independent conditions or dependent conditions based on the comparison.

20. The method of claim 16 , further comprising aligning the wearable device on the body part such that the impedance sensor or the miniaturized spectrometer are aligned radially with the subdermal structure on the body part, wherein the body part is approximately circular, approximately oval-shaped, or approximately elliptical, and wherein the body part comprises a radius extending from a center of the body part outward towards the dermal layer and perpendicular with the dermal layer.