Ask HN: Ideas for a prosthesis for sense substitution?

I'd love to become a cyborg (though prosthetic knowledge already makes me one). What new sense could I gain?

For sense substitution you usually need:

- a portable sensor (If possible something that moves with your body, this direct feedback makes learning much easier and might be key to a intuitive sense-like feeling. e.g. an IR-thermometer attached to a finger.)

- an interface / feedback (translating what the sensor senses to human sense. e.g. the thermometer reading to vibration)

feel free to submit known experiments also, I know there are quite a few. Yet I find it surprising, that most sensors that are portable and somewhat useful are already covered by the human body.