Obviously you should listen to Michael over me, but as a former YC founder with a robotics startup I agree that you should probably wait until you're more focused on growth than prototyping.
We see no need for funding (at least today) to finish our HW prototype; in fact if funded I am afraid a sizeable chunk of those 120k would be spent (wasted?) on moving to SV, getting some lab access, etc. The flip side is getting help earlier to shape the end product.