Before you can raise investor funding, you'll have to prove you have a business. That usually means creating a prototype and testing it with customers. By doing that, you prove that you can make the technology work, and you prove that it does solve a customer problem. That goes a long way toward reducing risk from an investor's point of view (see "What Investors Want").
Better yet - if you have paying customers, you've proven that customers agree that your solution has value.
That's the kind of proof you'll need to get investors interested. And that's why you need to utilize those bootstrapping funding strategies we talked about earlier - before you pitch investors. That's how you fund your company up to this point - where you've proven you have a business.