If the microneedles are part of a watch and the watch is simply worn on the wrist like a normal watch, how do you avoid (1) breaking the needles, or (2) contami

If the microneedles are part of a watch and the watch is simply worn on the wrist like a normal watch, how do you avoid (1) breaking the needles, or (2) contaminating the needles with random substances that are present on the user's skin or periodically enter between the watch and the skin? Could you replace the needles somehow? Can you avoid having to replace the needles frequently? Every worn device that I'm aware of that continuously interacts with the body in some way is either totally noninvasive (like a pulse oximeter that just shines light through a finger, or an EEG with external electrodes placed against the skin) or invasively and persistently attached to the bloodstream or an organ system (like an IV, an insulin pump, or an implantable defibrillator). Or do you have to somehow deliberately engage and retract the needles when putting on and taking off the watch? But wouldn't they break, or something, when the watch moves around on your wrist? Or do you apply a disposable or partly disposable sensor under adhesive tape to one part of the body, and then have the watch receive data from it using electrical or electromagnetic signals?