Cell-free biosensors: where have we been and where do we need to go?

Cell-free biosensors have the potential to become a low-cost, widely distributed technology. If deployed at scale, they can generate new large-scale data streams about human health and our environment, providing actionable information at the point of need. Here, we review the key technological advances of cell-free biosensors over the last five years and suggest a future path of technology development, including interfacing with circuits, devices, and materials that are becoming part of the next generation of biosensors. We then ask what is needed for these technologies to succeed at scale, focusing on lessons from field-deployment studies, policy, regulatory, safety, and other considerations to ensure alignment of technological developments with real-world necessities, market opportunities, and reliable use by non-experts.