Autonomic Technologies, maker of implantable devices that can soothe severe headaches, has raised $20 million in a second round of funding led by InterWest Partners. The Menlo Park, Calif. company is one of three biotech firms InterWest has recently backed, including antiviral creator Eiger BioPharmaceuticals and autoimmune drug maker Lycera.

Previously, Autonomic raised a $5 million first round of capital from Kleiner Perkins Caufield & Byers and the Cleveland Clinic.

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