Has your coworker/family member had too much (or too little?) coffee today? Take out the guesswork with this new fashionable headwear.

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Background:

Some people have noticeably different behavior depending on the amount of caffeine they have ingested so far that day.

An person’s level of caffeination may be useful information to others, allowing them to discern the reason for the under/over-caffeinated individual being overly lethargic or excessively manic.

Proposal:

Obviously there is no easy way for a person to visually detect whether or not their coworker has ingested zero, two, or five cups of coffee so far that day.

But we can fix this by making a “coffee hat,” which is simply a regular hat with a low power e-ink display (Figure 1) on the front that displays how many coffees the wearer has drunk so far that day.

The hat would operate as follows: 1) Whenever the scent of a new coffee is detected, it increments the meter by one bar. 2) Over time, as the caffeine is metabolized, the bar slowly decreases on its own.

Fig. 1: In this case, the caffeine-level bar (“A”) is approximately half full (B), showing that the user’s effective caffeine level is roughly equivalent to 2.5 cups of coffee (2.5 bars on meter). This situation could be arrived at by drinking three coffees in short succession (which would raise the meter to the “3” level) and then waiting an hour or two for the bar to naturally decrease (back down to the “2.5” level, as shown here).

Conclusion:

Could this also work with alcohol, or other substances? Maybe this could be a useful way of also tracking whether a person has taken important medications.

PROS: Fashion AND function together in the same article of clothing: amazing!

CONS: Could be difficult to wash.

Idea originally suggested by K. Graehl.

Originally published 2025-12-15.