Conditional storage

1. A method comprising:

obtaining, by a body-mountable device, sensor data that is measured by a sensor, wherein the body-mountable device comprises a data storage and the sensor, and wherein the body-mountable device has access to a power source;

determining that the sensor data is outside a predetermined range of values;

determining that the data storage has a threshold amount of available storage space;

determining that the power source is able to provide a threshold amount of power;

responsive to (i) the determination that the sensor data is outside a predetermined range of values, (ii) the determination that the data storage has the threshold amount of available storage space, and (iii) the determination that the power source is able to provide the threshold amount of power, storing the obtained sensor data in the data storage; and

otherwise, discarding the sensor data.

2. The method of claim 1 , wherein the body-mountable device comprises an eye-mountable device.

3. The method of claim 1 , wherein the power source comprises a battery included in the body-mountable device.

4. The method of claim 1 , wherein the power source comprises a photovoltaic cell included in the body-mountable device.

5. The method of claim 1 , wherein the power source comprises an external device that is accessible to the body-mountable device.

6. The method of claim 5 , wherein the external device provides power to the body-mountable device wirelessly.

7. The method of claim 1 , further comprising:

determining that the power source is expected to be able to provide a threshold amount of power to the body-mountable device within a threshold period of time.

8. The method of claim 2 , further comprising:

determining when the body-mountable device is within a wireless communication range of an external reader; and

based on the determination that the body-mountable device is within the wireless communication range, wirelessly transmitting at least a portion of the stored sensor data to the external reader.

9. The method of claim 1 , wherein storing the obtained sensor data in the data storage comprises storing the obtained sensor data in volatile memory.

10. The method of claim 1 , wherein storing the obtained sensor data in the data storage comprises storing the obtained sensor data in non-volatile memory.

11. The method of claim 1 , further comprising:

determining that a trigger event occurred.

12. The method of claim 11 , wherein the trigger event comprises an eye blink of a wearer of the body-mountable device.

13. The method of claim 11 , further comprising:

responsive to the determination that the trigger event occurred, ceasing the storing of the obtained sensor data in the data storage.

14. The method of claim 1 , further comprising:

determining that the obtained sensor data has been stores in the data storage; and

responsive to the determination that the obtained sensor data has been stored in the data storage, providing an alert.

15. The method of claim 14 , wherein the body-mountable device comprises a light source, wherein providing the alert comprises illuminating the light source.

16. The method of claim 1 , further comprising:

obtaining additional sensor data by the body-mountable device;

determining that (i) the additional sensor data is within the predetermined range of values, (ii) the data storage does not have the threshold amount of available storage space, or (iii) the power source is not able to provide a threshold amount of power; and

response to the determination that (i) the additional sensor data is within the predetermined range of values, (ii) the data storage does not have the threshold amount of available storage space, or (iii) the power source is not able to provide the threshold amount of power, preventing the additional sensor data from being stored in the data storage.

17. A body-mountable device comprising:

a sensor;

a data storage;

a power source;

a processor; and

a computer-readable storage medium having stored thereon program instructions that when executed by the processor cause the body-mountable device to:

obtain sensor data that is measured by the sensor;

determine whether the sensor data is outside a predetermined range of values;

determine whether the data storage has a threshold amount of available storage space;

determine whether the power source is able to provide a threshold amount of power; and

if the determinations indicate that (i) the sensor data is outside a predetermined range of values, (ii) the data storage has the threshold amount of available storage space, and (iii) the power source is able to provide the threshold amount of power, then store the obtained sensor data in the data storage; and

otherwise, discard the sensor data.

18. The body-mountable device of claim 17 , wherein the body-mountable device comprises an eye-mountable device.

19. The body-mountable device of claim 17 , further comprising program instructions that when executed by the processor cause the body-mountable device to:

determine that the power source is expected to be able to provide a threshold amount of power to the body-mountable device within a threshold period of time.

20. An eye-mountable device comprising:

a sensor;

a data storage;

a power source;

a processor; and

a computer-readable storage medium having stored thereon program instructions that when executed by the processor cause the eye-mountable device to:

obtain sensor data that is measured by the sensor;

determine that the sensor data is outside a predetermined range of values;

determine that the data storage has a threshold amount of available storage space;

determine that the power source is able to provide a threshold amount of power; and

responsive to (i) the determination that the sensor data is outside a predetermined range of values, (ii) the determination that the data storage has the threshold amount of available storage space, and (iii) the determination that the power source is able to provide the threshold amount of power, store the obtained sensor data in the data storage.