I just read a little blurb about new steps in cyborg generation (combining living tissue with engineered elements). It was in reference to this article, which I did not have access to: Raman R, Cvetkovic C, Bashir R. 2017. A modular approach to the design, fabrication, and characterization of muscle-powered biological machines. Nature Protocols. doi: 10.1038/nprot.2016.185. Here is the abstract. Novel aspects I had not seen before in this context: Optogenetic controls of muscle Muscles in soft hydrogels Muscle getting stronger from being exercised Linking the biological contractile elements with 3D printed skeletal elements. Optogenetic control is something new from Neuroscience. A light sensitive channel protein gene (previously engineered) is introduced genetically into one or more cells. Shining light on it opens the membrane channel letting ions enter, changing the membrane potential (charge across the cell membrane), and eventually in this case resulting in muscle contraction. This worked better than electrical stimulation (more confined stimulation?). Optogenetic control is often driven by laser light. In research, the light is often shined backwards through a microscope to illuminate (and control) activity in single cells. Muscle cell is a soft gel. Presumably, it is basically tissue culture media permeating a gel but if they are putting it into living organisms, it could be using the organism's own body fluids. This tissue culture media (or the host's body fluids) would provide the oxygen, nutrition, and waste product removal to support the tissue metabolic needs. This would be aided by the small size of what they made ("millimeter scale"). Since no vascularization (blood vessels) were mentioned, it seems likely that these cellular needs are only being met by diffusion through the gel (unless the host can grow blood vessels into the gel). This would put a limit on the metabolic capacity of their actuator. No Terminator yet! In order to make something like a younger Governator (that is the Terminator) would require the equivalent of a heart/vascular system to fulfill the higher rates of oxygen, nutrient, and waste product exchange that would be required. The vascular system would then need the equivalent of lungs, kidneys, and a nutrient source (digestive system/liver/fat storage...) to maintain proper functioning.