Back in 2012, I found myself in the basement of a couple self-styled biohackers, hooking up some electrodes to my temple. They were showing me a prototype of their "thinking cap," which they said increased focus by zapping your brain. Fast-forward to 2014 and Marc Andreessen — father of the modern web browser and the biggest name in tech investing today — just backed a $1.5 million seed round in Halo, a high-tech headband that promises to boost brain function through "neuromodulation," a fancy word for pumping electricity through your skull.

The Halo is the creation of Amol Sarva and Daniel Chao. Sarva is an entrepreneurial journeyman with the Peek email device and the Spotify-friendly Gramofon router on his resume. "After my company was sold I realized I had the freedom to pursue whatever was most interesting to me. So I made a list," says Sarva. He had read a story a decade earlier about increasing intelligence and creativity by directly stimulating the brain, and he says it "was the most amazing thing I had ever heard about and I had to pursue it."

Sarva hooked up with Chao, now Halo's CEO, and Brett Wingeier, both of whom had spent years working at NeuroPace, a company that creates medical devices that are implanted in the brain and use electric stimulation to alleviate seizures in epileptic patients. "That is fascinating and important work, but we wanted to try and create something that didn't require invasive surgery to use and had benefits for the average person," says Sarva. Recent studies at Oxford on transcranial electric stimulation have show it can improve math skills without an implant.

Together the three of them founded Halo Neuroscience. They began building simple prototypes using batteries and boards they bought at RadioShack, working with a community of DIY hackers. "It was pretty crazy," admits Sarva. During one early trial a hacker placed the electrodes too far forward, in front of his brain and directly next to his eyes. "I turned it on and there was this bright flash and then I was basically blind," he told me. The test had sent a direct blast into his optic nerve. "Luckily it cleared up after a few minutes," says Sarva. "We're much better informed now about which parts of the brain we need to stimulate."

The company isn't revealing much about its product yet, citing a range of intellectual property and safety priorities it needs to keep in mind as it seeks federal approval from the FDA. Sarva did say that the company plans to use a range of electromagnetic approaches, including electricity, magnetic fields, infrared light, and radio waves. Clinical trials are expected to start later this summer.