The Lewis lab's main contribution here is the scale and precision of 3D printing. These batteries are not immediately useful (although there are sensors and other electronics that are an order of magnitude smaller than the batteries that power them, and in the future micro-scale batteries could overall reduce the size of these electronics). They are not powerful or robust, but they are precisely assembled. This type of 3D printing will enable future miniaturization of electronics and be especially useful at the interface of electronics and biology. For instance, current 3D printers have resolution several orders of magnitude above the scale of features in tissues. Increasing the resolution of 3D printing enables tissue engineering at a scale similar to actual biological features. Batteries are just a flashy and potentially useful application of this fundamental printing technology.