Small is big for Murata: The Japanese electronics maker has developed the world's tiniest version of a component known as the capacitor. And that's potentially big business. Capacitors, which store electric energy, are used in the dozens, even in the hundreds, in just about every type of gadget—smartphones, laptops, parts for hybrid cars, medical equipment and digital cameras. Smaller componentry allows for other innovations and improvements from thinner devices to longer battery life. The latest capacitor, measuring just 0.25 millimeter by 0.125 millimeter, is as tiny as the period at the end of this sentence. Murata Manufacturing Co.'s focus on...