Ok, back to biohacking gadgets – Joule: Wear your Caffeine | Indiegogo.

The Joule Caffeine Bracelet Provides Convenient, Consistent, All-Day Energy with No Crashes, No Long Lines at the Coffee Shop, No Stained Teeth and No Calories! The Joule caffeine bracelet is a bracelet with a slot for you to snap on a transdermal caffeine patch. These patches work in a similar fashion to a nicotine patch or other transdermal medication patches. The caffeine is administered gradually for a steady supply of caffeine and energy without any of the typical energy crashes, jitters or other negative effects of consuming your caffeine through beverages.

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Interesting claims. Does it work? Well, there are a few caffeine patches out there, so try those and see if they work for you, you can also make your own.