NEW BIO-THERMAL BATTERY

• by peter
• 2008-04-11 04:04:28
• Batteries & Leads
• 2762 views
• 1 comments

There is a new battery that is being developed for pacemakers which will enable pacemakers to last at least 30 years even in ICDs. Although there are a number of avenues being persued on the battery life front to replace the Lithium Iodine battery, I am convinced that this is the one that will win the day and give electrophysiologists a bit of an easier life. The new battery under developement is called a Bio-Thermal battery and works by taking advantage of the temperature differential/gradient that exists in many parts of the body including the prefered implantation site below left shoulder site. For this new Bio Thermal battery to work it only needs a temperature differential of 2 degrees centigrade. The electrical generator uses 10,000 thermocouples linked in series. They are made from a semiconductor material called Bismuth Telluride. The material is doped with impurities to give two different types of Bismuth Telluride, one with a surplus of electrons giving a negative type (called N type) and the other with a positive charge (Called P type). The same principle is applied in the manufacture of transistors using silicon. When these two different types of material P and N are connected to gether the result is a very high performance thermocouple (a thermocouple generates a small amount of energy/voltage proportional to temperature) . Wire a lot of these in series and hey presto you have a virtual everlasting battery that gets its power from your body heat or rather the difference in temperature between your skin area and the tissues below. The genearator continuously charges a battery in the pacemaker to give a safety margin.The surface area required by the new battery in order to run is only 2.5 cm by 2.5 cm or approx 1 inch square.My only concerns are that firstly there are 10,000 connections and only one needs to fail to make the generator stop working. Also if the pacemaker were to move so that it was not picking up a temperature differential it would not generate any power. I dont think these are major concerns though. We all ready have effectively 10s of thousands of connections in the microcircuit/microcontroller in our pacemaker. The current failure rate of pacemakers I believe is .02 percent , which is 1 in 5000 devices. The battery should be available within 10 years. Something to look forward to.
If you want some more technical info on this I could provide it but it is not easy to understand. Cheers Peter