Considering that pacemakers are invasive hunks of metal surgically placed inside the body to regulate heartrates, Michael Jenkins et al.'s development of a laser pacemaker is exciting to say the least.
Although only tested on quail embryos thus far, Michael Jenkins et al. have successfully used pulses of light to regulate the pace of their hearts. This paves the way for "human pacemakers that don't require invasive surgery or heart-weakening electrodes," according to Gizmodo. Of course, it will take some time to transition from quail embryos to humans.