There are at least three ways for achieving human-electronic interfaces; physical implants, wearables and a third as yet unconsidered possibility, exploiting the human bacterial biome.
There are 500 to 1000 classes of bacteria.
Bacteria can be upgraded and functionalized for various augmentation purposes.
1. Add computer memory to bacteria or nanobot bacteria equivalents.
2. Add computer processing to bacteria.
3. Create respirocyte like capabilities [supply extra oxygen to the body]
4. Provide energy generation or energy storage [chemical for the body or electrical for cyborg systems]
5. Provide sensor functions or carry other electronics
From Melanie Swan:
Easy upgrade and maintenance
The continual turnover, ingress and egress of bacteria in humans means that upgrade cycles and retirement of dead or non-functioning elements could occur seamlessly. Bacterial updates could be printed regularly from a 3d printer or automatically dispensed in smarthome air or water. Mechanically, the updates might be delivered through the air, in the shower, or by a nutrient blanket during sleep.
Enhancing the human bacterial biome would really just be extending the life support functionality it already provides and could be a nice intermediary step to the more robust bionanodevices and nanobots envisioned in molecular manufacturing. Existing bacteria could be enhanced, much of the human microflora does not appear to be doing anything anyway, or additional bacteria could be engineered and brought on board.