For those whose hearts often go off beat, pacemakers(心脏起搏器) are life savers. By providing a small electrical support at the right moment, they can keep a heart working properly. Their main problem is that they use batteries. Even the best of them will run out of energy, and changing the batteries requires operations. Since operations are usually best avoided, the search has been on for long-lasting batteries. Different choices have been explored for a long time. Today, pacemakers with lithium(锂) batteries last between 5 and 15 years.
Zhang Hao, from Shanghai Second Military Medical University, and Yang Bin, from Shanghai Jiao Tong University, tried a way to refill a pacemaker’s battery with electricity(电) by getting energy from inside the body. They report in the magazine ACS Nano that they have also used the heart muscle(肌肉) itself to work. Earlier efforts by other scientists to use heart muscle power to run pacemakers depend on piezoelectric materials(压电材料). These materials can be connected to a beating heart and produce electricity when they are slightly deformed(弯曲). This has worked, but not well enough: the output has rarely been over 5 microwatts(微瓦), while most pacemakers require at least ten.
Dr Zhang and Dr Yang believed that they could improve the matters by making their piezoelectric materials more dramatically deformed, and then produce 15 microwatts, because the more deformed, the more electricity will be produced. They put their idea to the test in a 50kg pig. It made enough electricity for the pacemaker to work as expected.
Whether such an idea will pass human tests remains to be seen. But if it does, the days of pacemakers that need battery changes through operations may not last long.