One of the problems with "wearables"? Everyone knows you're wearing one.

They can see it on your wrist, tracking your pulse or paces. Maybe they can see it on your glasses. Maybe they judged you and ran away. Maybe they started to tell you about their exercise routine.

All of that--and a few more important things--might change in the future, thanks to ideas like the one Google was awarded a U.S. patent for earlier this week. The patent--which was initially filed on July 26, 2012--is for a contact lens that "harvests light received and generates power from the harvested light."

In other words, the patent is for a solar-powered contact lens. What's more, these contact lenses also possess a fascinating set of potential capabilities. Here's a rundown of those capabilities, based on descriptions in the patent. 

1. Monitor body temperature and blood-alcohol level. 

As Mike Murphy points out in his story about the patent on Quartz, the patent suggests that the contact lens could potentially "send information back to another device about the wearer's temperature or blood-alcohol level."

2. Help wearers handle allergies. 

Specifically, the patent reads that one of the sensors "can sense any number of biological, chemical and/or microbiological features in an environment including, but not limited to, levels of hazardous materials, levels of allergens, the presence of various organisms or species or the like." Those allergens include tree or grass pollen, pet dander, and dust mite excretions.

3. Scan barcodes or price tags. 

The patent specifies circumstances under which the contact lenses and the devices you'd use with them can "receive information detailing electronic coupons, pricing, warranty information or the like." A cashier wearing the contact lens would be able to scan and process coupons and price tags very quickly. The cashier's lenses would essentially become the scanner. 

4. Track glucose levels. 

What's more, the patent notes that the lens can potentially "include circuitry for outputting the sensed information to a reader." That would give a doctor or a parent the ability to gauge if the level of the substance were too high or low. As Murphy notes, this sounds like "an extension of another Google lens project, which aims to help diabetics track their glucose levels."

5. Generate power from both the sun and ambient light sources. 

The lenses include a "photodetector" which "harvests light emitted from a device and generates power from the harvested light." That photodetector, notes the patent, can be "a photovoltaic cell or a solar cell."

In this regard--their potential use of transparent photovoltaics--the lenses are comparable to what MIT's Dean of Innovation, Vladimir Bulovi?, is working on. For example, one of Bulovi?'s three startups, Ubiquitous Energy, makes clear coatings for use on the displays of Kindles or another mobile devices. "You'd never have to recharge it again," says Bulovi?. The reason? The coating would catch enough solar power and ambient light to give the device a seemingly infinite amount of power.

The coating also has the capability to power office buildings, if you apply it to the windows of the buildings. In addition, it could provide perpetual power to hearing aids, if you put the coating on, say, your eyeglasses. Google's patent might one day do for contact lenses what Ubiquitous Energy's coating can do for conventional spectacles. 

6. Talk to your other devices.

The patent mentions that the contact lenses should be able to communicate with devices such as "personal digital assistants (PDAs), audio/video devices, mobile phones, MPEG-1 Audio Layer 3 (MP3) players, personal computers, laptops, tablets." 

7. Authenticate identities.

It's just one line in the patent, but it's there: "Retinal analysis of a user can be performed and an optical signal transmitted in response to an authentication request," reads the document. How this would work with the lenses isn't explicit in the patent. Meanwhile we can content ourselves with sci-fi renditions of retinal verifications: