Understanding the anatomical structure and function of the brain is a longstanding goal in neuroscience. Electrical and optical techniques offer distinct and complementary advantages that, if used together, could offer profound benefits for studying the brain at high resolution. Combining these technologies is challenging, however, because conventional metal electrode technologies are too thick (>500nm) to be transparent to light, making them incompatible with many optical approaches. To help overcome these challenges, the Defense Advanced Research Projects Agency (DARPA) has created a proof-of-concept tool that demonstrates much smaller, transparent contacts that can measure and stimulate neural tissue using electrical and optical methods at the same time. This tool could be used to inform and improve neural interfaces, such as those used to control dexterous functions made possible with advanced prosthetic limbs.