Bioelectronic medicine player electroCore has set itself up for the next chapter in its story with a $70 million round. The VC wing of Merck was among the investors to return for the series B, which will enable electroCore to commercialize its approved headache product while advancing research in other indications.

ElectroCore is one of a clutch of medical technology firms trying to treat conditions by stimulating the vagus nerve. Such neuromodulation has emerged as a way to address hard-to-treat epilepsy cases in recent decades. The first wave of products required implantation. But electroCore has set itself apart by developing a noninvasive stimulation device and going after other indications, most notably cluster headaches.

The FDA signed off on the use the device—gammaCore—in a subset of headache patients in April, prompting electroCore to seek to add to the $50 million it raised in 2013 and 2014.

Core Ventures II stepped up to the plate again for the series B, leading a round that gives the firm $70 million to play with. ElectroCore hit that high thanks to “significant participation” from the VC wing of Merck—which co-led the series A—and assists from new backers including Gakasa and investment vehicles associated with former Fidelity Magellan Fund manager Jeffrey Vinik.

Having secured its financial future, electroCore now has the means to work toward its goal of distributing up to 1,200 gammaCore devices to patients at no cost for the first two months. That is part of the company’s efforts to build a commercial registry.

The rollout is limited to adults with episodic cluster headaches who need help managing the pain associated with their conditions. ElectroCore initially swung for the broader cluster headache market but its device failed to outperform a sham therapy in this population. An analysis of the subgroup of patients with episodic, not chronic, cluster headaches suggested the device is more effective in this population, setting electroCore on the path to the de novo FDA approval.

ElectroCore is now working to broaden use of the device. A 510(k) label expansion covering the acute treatment of migraine is already in front of the FDA. And the company is working with partners to assess the effect of noninvasive neuromodulation in other indications.