So much as been written about this topic and you can read many great books on the subject.

A simple chronology might look like this:

1) Months 1-6

who: friends and family
how much: $50-100k
where: out of your house, or a friend's office
what: initial marketing review, initial business plan, a concept device

2) Months 6-12

who: Innovation Works, The Digital Collaborative, The Pittsburgh Lifesciences Greenhouse
how much: $100-250k
where: in anincubator, or a shared office suite
what: first prototype, first patent application

3) Months 12-24

who: Individual Angels, Angel Groups such as Blue Tree and Advanced Global Technologies, Innovation Works, The Digital Collaborative, The Pittsburgh Lifesciences Greenhouse
how much: $500k-1M
where: in your own office space
what: first sales, if you are lucky you will have repeat sales

4) Months 24-48
who: your current investors, your customers or corporate partners, venture capitalists
how much: $2-10M
where: in your own office space
what: a path to positive cash flow