Scientists at Clemson University in the US have rigged an HP Deskjet 500 printer to make microscope slides full of living cells. It spits out a a special cell-packed ink from the printer's standard cartridge. The process creates cells with temporary permeability in the cell walls, and the holes in the cells are large enough to allow fluorescent molecules to be injected. That glowing stuffing illuminates the membranes, so researchers can get a look at what's happening inside the cells. When studying a heart, for example, the technique can be used to examine how the cardiac muscles respond to mechanical force and fluid shear.