The Cochlear Implant

Figure 1. A Sample Cochlear Implant (Source)

Brief: The cochlear implant is a surgically implanted electronic device that provides a sense of sound to someone who is deaf or hard of hearing in both ears. They work with a microphone and a series of electronics that bypass the regular hearing pathway. The electronic components trigger electrodes placed in the cochlea and stimulate the cochlear nerve. However, there is a small level of controversy associated with the devices especially within the deaf community. They feel that it is insulting to people who learned sign language as their first language. It consists of 5 main parts: the microphone, a speech processor, a transmitter, a receiver/simulator, and an electrode array embedded in the cochlea.

The Intraocular Lens

Figure 1. Sample types of Intraocular lenses (Source)

Brief: The intraocular lens is generally used to treat cataracts and myopia. The purpose is to replace the damaged or cloudy natural lense with a fully functional light focusing artificial lens. In 1946, Dr. Harold Ridley was in the process of removing a cataract from a patient when a medical student questioned him that he removed the cataract so why didn't he put anything else as a replacement. This question got him thinking. Because he worked with casualties of war with RAF he noticed that often fragments of the plane windshields would become lodged in pilots' eyes. However, the body did not reject the plastic known as polymethyl methacrylate. It was from that point did he start working on designing an implantable PMMA lens that could replace the cataract.

The Artificial Heart

Figure 1. Early Model Artificial Heart (Source)

Brief: The artificial heart has long been considered one of the holy grails of modern medicine. Although earlier technology has made it difficult for the heart to be replaced simply because of physical and mechanical limitations, with advancements in medical technology it is now possible to be implanted with an artificial heart that can last for a few years before replacement. The first artificial heart was made by Vladimir Demikhov in 1937 and implanted into a dog. However, because of compatibility issues, it was unable to be used in humans. Later, with changes to the heart itself including the valves and materials, the first heart for human use was invented in 1969.

The Defibrillator

Figure 1. Early Commercialized Defibrillator (Source)

Brief: Another tool commonly associated with the medical care field is the defibrillator. But to understand the device itself we must first take a look at the underlying principle of defibrillation. Defibrillation is a therapeutic dose of electric current to the heart to depolarize a critical mass in the heart muscle, allowing the body to return to a natural pace. In the previous post referring to the galvanometer, Galvani discovered that electrical currents can cause muscle contraction in 1791. However, the application of electricity in the field of medicine was primarily to confirm whether or not a person was truly dead. Eventually in 1850, Karl Ludwig applied the current to a dog's heart and made it quiver. There are currently 2 types of defibrillation devices: Automated External Defibrillators (AED) and Implantable Cardioverter Defibrillators (ICD). 

The Galvanometer

Figure 1. Tangent Galvanometer

Brief: The Galvanometer is a device used to detect the electric current flowing through an object. The current disrupts the magnetic field in the coil of the device. The word galvanometer was first attributed to Luigi Galvany in 1836 when he realized that the electric current would make a dead frog's leg jerk. The earliest galvanometer relied on Earth's magnetic polarity to reset the device after every use. Eventually improvements led the galvanometer to its final form as the Mirror galvanometer. This device was designed by William Thomson (Lord Kelvin) uses permanent magnets hung by a thread between a coil with a mirror affixed to the magnets. The light would bounce of the mirror onto a scale when a current would displace the magnets holding the mirror.

The Stethoscope

Figure 1. One of the earliest cylindrical stethoscopes

Brief: The stethoscope was invented in 1816 by a young doctor by the name of Rene Theophile Hyacinthe Laennec. Previously, the only way to listen to a patient's heartbeat and breathing was to place the ear to the chest (Immediate Auscultation). However, being embarrassed by doing so to a young female patient, Laennec used some quick thinking and rolled up 24 sheets of paper into a cylinder. By placing one end on the patient's chest and the other to his ear, he noted that the sound was not only louder, but clearer as well. At first Laennec was hesitant to name the device as he thought that something so intuitive would not require a name, but he eventually came up with one because he disliked the ones his colleagues gave and thus the Stethoscope was coined.

The Surgical Scalpel

Figure 1. Early Roman Bronze Scalpels

Brief: The knife was one of the earliest tools of invention by humans and the tool itself can be applied in many ways. However, the surgical scalpel did not differentiate itself from the rest of the knives until the time of Hippocrates, roughly 300 B.C. He described them as macairion, derived from machaira, an old sword with a broad cutting blade on one edge and a sharp point. Originally scalpels were made of bronze and other easily accessible metals and remained that way until iron and steel became easier to manufacture.

Welcome to My Website!

Hello everyone, The purpose of this blog will be to provide information about past and present medical devices in a quick and easy to read format. Additionally I will try to provide an image if available and links to other sites which hold more information.

Starting in the following week I will attempt to cover at least 1 to 2 devices a week which will vary in nature of their relation to the human body. If you enjoy reading about medical technology in general or would like to get ideas or research started on a project, feel free to follow or browse the posts.