Pacemaker batteries

Because normal radioisotopic decay lowers the thermal output by about 2.5%/yr in these units, they are purposefully overdesigned for beginning of life conditions. Several of these generators have successfully operated for as long as 28 years. This is approximately equal to the half-life of the strontium-90 isotope used in the heat sources. The original SNAP-7 series immobilized the strontium-90 as the titanate, but the more recent ones have used it in the form of the fluoride, which is also very stable. A number of tiny nuclear-powered cardiac pacemaker batteries were developed, which have electrical power outputs of 33—600 p.W and have been proven in use (17). 

What point defects are vital for the operation of Lil pacemaker batteries ... 

Lithium iodide pacemaker batteries use lithum iodide as the electrolyte, separating the lithium anode and the iodine anode. The function of the electrolyte is to transport ions but not electrons. Lithium iodide achieves this by the transport of Li+ ions from the anode to the cathode. This transport is made possible by the presence of Li vacancies that are generated by the intrinsic Schottky defect population present in the solid. Lithium ions jump from vacancy to vacancy during battery operation. 

Using only materials that are available in your school chemistry laboratory, design a pacemaker battery. Find out what voltage is appropriate for a pacemaker. Be sure to outline all design considerations. 

The high reliability and the complete absence of faults such as electrolyte leakage or gas generation make the lithium-iodine solid state battery a particularly suitable device for powering implanted electronic devices, and it is now widely used in the cardiac pacemaker industry. The design and construction of Medtronic Inc, pacemaker batteries are shown in Fig. 9.12. A typical unit, such as the Enertec Alpha 33 , has dimensions of 33.4 mm X 27.4 mm X 7.9 mm, giving a total volume of 6.0 cm3 and a mass of 22 g. The cell has a completely welded construction and uses a specialized... 

Fig. 9.13 Projected practical capacity of a lithium-iodine pacemaker battery (Enertec Alpha 33) as a function of current drain. (By courtesy of Medtronic Inc.)...

Mallela VS, Ilankumaran V, Rao NS. Trends in cardiac pacemaker batteries. Ind Pacing Electrophysiol J. 2004 4(4) 201-212. 

There was still more to come, and not only from the big, well-heeled companies and universities. At the University of Arkansas, Allen Hermann, chairman of the physics department, decided to go for a high Tc mark. Co-inventor of a heart pacemaker battery and a jazz trombone player of some note (stints with Ella Fitzgerald and Lionel Hamp-... 

Battery characteristics Lithium is the least dense of aU nongaseous elements, with a density of only 0.534 g/mL. The lightweight lithium contributes little weight to the small, detachable battery pack, which is a circular disk only about 5 cm by 1 cm in size. The pacemaker battery pack is implanted imder the patient s collarbone and has a life expectancy of about seven to ten years, depending upon how often it is needed to stimulate the heart. 

Photographic chemicals, dyes Rubber antioxidants Adhesive bandages Pacemaker batteries... 

Solid-state and wet lithium cells have replaced the conventional Rubin-Mallory zinc/mereury pacemaker battery using aqueous NaOH solutions. Both types of lithium cell exhibit higher energy densities than conventional cells, e.g. Zn/HgO with 100 W h/kg > or 0.35 W h/cm or Zn/MnOj with 0.1 to 0.2 W h/cm " >, and a far longer shelf-life, e.g. a lead-acid battery exhibits a self-discharge rate of 1 % per day the Zn/MnOj-cell of 20 % per year... 

Electrical properties allow them to be used as metallic conductors - Cu, Ag as semiconductors - Si, GaAs as superconductors - NbjSn, YBa2Cu302 as electrolytes - Li in pacemaker batteries as piezoelectric - a-quartz in watches. 

Liang CC, Holmes CF (1980) Lithium pacemaker batteries - an overview. In Owens BB, Margalit N (eds) Proceedings of the symposia on power sources for biomedical implantable applications and ambient temperature batteries, vol 80-84, pp 27-33... 

Parker B (1978) Obituary a vindication of the zinc-mercury pacemaker battery. Pacing Clin Electrophysiol 1 148-149... 

Figure 20 Isotopic powered cardiac pacemaker battery. (UKAEA)...

Technical Information Report - Systems used to forecast remaining pacemaker battery service life, Washington, DC, Association for the Advancement of Medical Instrumentation, 1998, Document AAMI TIR No. 21 - 1998. 

General Electric has now announced the successful development of heart-pacemaker batteries of this type with bromine cathodes, giving an open-circuit voltage of 3.6 V, which are expected to have an operating life of ten years. 

Lithium batteries are used wherever a reiiabie current is required for a iengthy period.The photograph shows a smaii pacemaker battery. 

This type of cell is highly reliable, and it is commonly used in cardiac pacemaker batteries which... 

Batteries require the transfer of ions from one electrode to another. Originally in battery technology, the electrolyte was a fluid. However, batteries for uses in space craft and medical apphcations, such as cardiac pacemakers, require that the electrolyte should be a permeable sohd. The original pacemaker batteries used a mixture of poly(N-vinylpyrrohdone) mixed with a low molar mass plasticiser and doped with a high concentration of a salt. 

One example is the lithium iodide electrolyte in a typical cardiac pacemaker battery. Another one is the mixture of lithium halides with - for immobilization -magnesium oxide in some thermal batteries, and a further one a mixture of lithium iodide with aluminium oxide or silica for some memory back-up systems. 

The first lithium/iodine cardiac pacemaker battery was implanted in 1972. This type of battery proved to be very successful in this field and for other applications, too. The special features of this solid state battery are explained with its technique, which is limited with its extremely high energy density and reliability, especially for low rate applications. This technique is based firstly on the electrode couple of lithium and iodine with its high energy content - the OCV of the lithium/iodine cell is 2.80 V -and secondly on the favorable fact that the product of the cell reaction, the lithium iodide (LiJ), forms very tight and continuous layers between the active material of the electrodes, which are acceptable ionic conductors with negligible electronic... 

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