- Posted by doEEEt Media Group
- On September 11, 2019
Capacitors are essential components in a wide range of electronic systems including smartphones, household electric appliances, electric vehicles, and medical devices to name a few. Capacitors for use in life-supporting and non-life-supporting medical devices are required to have high reliability, and they are taken through stringent screening checks. Moreover, unlike capacitors for use in consumer electronics, these components have special evaluation criteria and service life requirements.
Passive components have a wide range of uses in both implantable and non-implantable medical devices. Although all medical applications demand compact and high-reliability capacitors, implantable medical devices have the most stringent performance demands.
Capacitors for use in implantable medical devices
There are a wide range of implantable medical devices used in today’s treatment procedures. These devices include artificial cochlea, cardioverters, defibrillators, insulin pumps, gastric stimulators, neuro-stimulators and pacemakers. Since implantable medical devices are embedded in the body of a patient, it is necessary to ensure that they have insignificant side effects on a person.
Capacitors for use in implantable medical devices are required to have high reliability, large capacity and be small in size. As compared to capacitors for use in portable and wearable medical devices, these components are subjected to a more stringent screening process. They are also specially designed to ensure that they offer a longer service life. In addition, capacitors for use in life-sustaining medical devices have stricter change control requirements.
Solid tantalum capacitors are widely used in the electronic circuits for both life-supporting and non-life-supporting devices. The popularity of these capacitors is mainly due to their impressive self-healing capability and inherent reliability. In addition, due to the high volumetric efficiency of these capacitors, it is possible to produce components with high capacitance values in small case sizes. Furthermore, unlike most types of capacitors, solid tantalum capacitors do not have any known wear-out mechanism.
Apart from tantalum capacitors, multilayer ceramic (MLC) capacitors are also commonly used in implantable medical devices. MLC capacitors that are designed for critical medical applications are usually compact in size and offer high reliability and large capacity. Use of compact components allows the realization of high-density implantable devices with little or negligible effect on a patient’s body.
Capacitors for use in non-implantable medical devices
This class of capacitors consists of components that are designed for non-critical medical applications. These capacitors are used in various devices including diagnostic imaging equipment such as X-Ray units, and CT and MRI scanners. Capacitors that are designed for use in portable and wearable devices such as electrocardiograms, ultrasonic echo devices, and blood gas analyzers are also in this category.
Compared to capacitors for implantable medical devices, components for use in non-critical medical applications have less stringent reliability requirements. However, unlike commercial-grade capacitors, components for use in this class of medical applications are required to have higher reliability and larger capacity. In addition, today’s non-critical medical applications demand components that are compact.
The two types of capacitors that are commonly used in non-implantable medical devices are tantalum and multilayer ceramic capacitors. Tantalum capacitors for use in non-implantable medical devices are designed to offer low leakage. Unlike standard commercial-grade capacitors, these components are usually taken through special screening process to achieve the required high reliability.