JPH069615B2 - Method of manufacturing electrode for cardiac pacemaker - Google Patents

Description

The present invention relates to a method for manufacturing an electrode for a cardiac pacemaker.

(Prior Art and Problems Thereof) A cardiac pacemaker is composed of a main body including a control unit, electric wires and electrodes. The performance required for electrodes, especially for implantable cardiac pacemakers, is that the electrodes easily adhere to the heart, the polarizability of the pulse generated by the pacemaker is low, and the signal from the heart is detected. The impedance (input impedance) may be small, and the impedance (output impedance) when a signal is emitted to the heart may be large. Therefore, conventionally, Pt or a Pt alloy that is harmless to the living body and has high electric conductivity is used to reduce the physical size of the electrode to increase the output impedance, reduce the polarizability, and reduce the input impedance. In addition, the surface of Pt or Pt alloy is mechanically roughened by sandblasting or glass beads to increase the substantial surface area to improve the polarizability and the input impedance. Especially, the polarizability and the input impedance are improved. There is no sufficient effect, and improvements in these aspects have been desired.

(Object of the Invention) The present invention has been made in view of the above demands, and is capable of minimizing the physical size of the electrode in order to increase the output impedance and reducing the polarizability and the input impedance. It is intended to provide a method. In particular, reducing the polarizability leads to prevention of malfunction of the pacemaker, extension of battery life, and enhancement of responsiveness to the heart.

(Structure of the Invention) The present invention is characterized in that an electrode made of Pt or a Pt alloy is coated with a mixture of Pt and IrO ₂ .

The present inventor has conducted extensive studies to reduce the polarizability and the input impedance. As a result, in order to reduce these, in addition to the substantial surface area, the affinity for hydrogen ions and chloride ions in body fluids is small. Moreover, it has been found that the polarizability and the input impedance can be reduced very effectively by using a material having excellent catalytic performance for discharging these ions for the electrode. That is, in order to reduce the polarizability, the hydrogen and chlorine ions at the interface between the electrode and the body fluid are discharged in the shortest possible time, and the ions on the electrode are atomized or molecularized in the shortest possible time. As a result, the input impedance is also reduced. The present inventors conducted an experiment to find a material having excellent catalytic ability for these hydrogen ions and chlorine ions, and as a result, IrO ₂ was found to be most suitable.

In the present invention, the electrode material is limited to Pt or Pt alloy because these materials are harmless to their birth and have excellent electric conductivity. Further, the reason why the coating layer is limited to the mixture of Pt and IrO ₂ is that Pt enhances the adhesion strength between the coating layer and the base and is excellent in the catalytic performance against IrO ₂ hydrogen ion and chlorine ion.

Next, the manufacturing method of the present invention will be described in more detail.
First, chloroplatinic acid and iridium chloride are selected from predetermined amounts, preferably in the range of Pt-Ir 5 to 95 wt%, and dissolved and mixed in an organic solvent. For this composition, if the coating strength is required, a large amount of Pt should be selected, and if polarization characteristics are required, a large amount of Ir should be selected.

This solution is applied on an electrode made of Pt or Pt alloy. As a coating method, any method such as dipping, brush coating and spraying may be used. The electrode is naturally dried or dried at a temperature of 200 ° C or lower, and then fired at a temperature of 400 to 700 ° C and an oxygen partial pressure of 1/5 atmospheric pressure or more. By firing in an oxidizing atmosphere, iridium chloride is decomposed and oxidized to IrO ₂ at the same time, but Pt is not oxidized.
-IrO ₂ coating film can be obtained. The film thus obtained has an extremely large surface roughness due to decomposition and heat shrinkage, and thus has a large real surface area and is excellent in polarization characteristics and input impedance characteristics. In the present invention, this coating, drying, and baking are repeated twice or more. The reason is that cracking occurs due to thermal contraction once, and the Pt of the base is limited.
Alternatively, the Pt alloy is exposed and the characteristics deteriorate.

Further, the coating does not have to be applied to the entire surface, and only the portion contacting the body fluid is sufficient. Further, it was confirmed that the catalytic ability can be sufficiently exhibited if the coating thickness is 0.5 μm or more.

(Example) An example of the electrode for a cardiac pacemaker according to the present invention will be described together with a conventional example.

First, a conventional example will be explained. An electrode 1 for a cardiac pacemaker having a size and shape shown in FIG.
The effective surface area was increased by blasting 50μ glass beads.

Explaining Example 1 next, an electrode 1 for a cardiac pacemaker having a size and shape shown in FIG. 1 is made of Pt, and Pt—IrO ₂ is coated on the head 2 by baking, and the heart shown in FIG. The pacemaker electrode was obtained. The manufacturing conditions are chloroplatinic acid and iridium chloride in Pt-Ir33wt.
%, Dissolved in butanol, mixed, brushed, dried at 100 ° C., baked at 500 ° C. in air for 10 minutes,
This coating, drying and baking were repeated 5 times. The thickness of the coating film 3 at this time was 1.0 μm.

Next, a second embodiment will be described. An electrode having the size and shape shown in FIG. 1 was made of Pt-Ir 5 wt%, and Pt-IrO ₂ was coated on the head 2 by baking to prepare an electrode for a cardiac pacemaker shown in FIG. Got The manufacturing conditions are such that chloroplatinic acid and iridium chloride are weighed so as to be Pt-Ir75wt%, dissolved in butanol, mixed, and then applied by spraying.
After drying at 100 ° C., baking was performed at 550 ° C. and an oxygen partial pressure of 1 atm for 10 minutes, and the coating, drying and baking were repeated 10 times. The film thickness at this time was 1.0 μm.

The electrodes for cardiac pacemakers of the conventional example and Examples 1 and 2 obtained in this way were measured for polarizability from pulse waveforms by the test circuit shown in FIG. 3, and input impedance was measured by the test circuit shown in FIG. Was measured, and the results shown in Table 1 below were obtained.

In FIG. 3, 10 is an electrolytic cell, solution 11 is NaC 9 g, water 1
, Ethanol 1, the cathode 12 in the solution is a cardiac pacemaker electrode, the anode 13 is a 12 cm ² Ti plate, and the distance between the electrodes is 50 mm. 14 is a constant current power supply of 10 mA, and 15 is an oscilloscope for measuring waveforms.

In FIG. 4, 10 to 13 are the same as those in FIG. 3, and therefore their explanations are omitted. 16 is a 100 mV, 50 Hz power supply, 17 is a 10 Ω shunt resistor, and the input impedance is measured.

Calculation of the polarizability of the above, those derived from the V _max and V _p of the P pulse waveform of FIG. 5 as follows.

Polarizability (%) = (V _p / V _max ) × 100 Further, the calculation method of the sensing impedance is as follows.

As is clear from Table 1 above, it can be seen that the electrodes for cardiac pacemakers of Examples 1 and 2 have remarkably low polarizability and the input impedance is orders of magnitude smaller than that of the conventional electrodes for cardiac pacemaker. .

(Effects of the Invention) As described in detail above, according to the method for manufacturing an electrode for a cardiac pacemaker of the present invention, the physical size can be made as small as possible and the surface roughness can be made large, and further IrO ₂ having excellent catalytic activity can be obtained. Since it is coated, the polarizability is extremely low, the responsiveness from the heart is high, the power consumption is low, the sensing impedance is extremely low, and it is possible to obtain an extremely reliable electrode for a cardiac pacemaker. There is an excellent effect.

[Brief description of drawings]

FIG. 1 is a diagram showing the shape and dimensions of a conventional cardiac pacemaker electrode, FIG. 2 is a diagram showing an electrode having a coating film of Pt and a Pt group oxide obtained by the example, and FIG. 3 is a polarizability. FIG. 4 is a diagram showing a test circuit for measurement, FIG. 4 is a diagram showing a test circuit for measuring sensing impedance, and FIG. 5 is a diagram showing a pulse waveform as an element for calculating polarizability.

Claims (1)

[Claims] 1. A method for producing a Pt and IrO ₂ coated electrode on a cardiac pacemaker electrode made of Pt or a Pt alloy, wherein a predetermined amount of chloroplatinic acid and iridium chloride are dissolved and mixed in an organic solvent. And then Pt
Alternatively, it is applied on Pt alloy and dried, and the temperature is 400 to 700 ° C,
Oxidation and firing are performed at an oxygen partial pressure of 1/5 atm or higher, and the steps of coating, drying and firing are repeated at least twice, and Pt-
A method for producing an electrode for a cardiac pacemaker, which comprises obtaining an IrO ₂ coating film.