The Evolution of Medical Devices – From Pacemakers to Pocket ECG

People are now living at least 20 years longer than they did a hundred years ago, and one of the reasons for this is the dramatic transformation in medical technology. Innovations in medical devices have immensely contributed to better quality of lives among patients and improved health outcomes for a range of diseases and disabilities. Here’s a look at a few medical devices that are commonplace today that underwent monumental transformations since they were invented:


A stethoscope is a device used by doctors to listen to patients’ breathing and heartbeats. It was invented in 1816 by a French doctor René Laennec as an alternative to having to awkwardly place the ear directly over a patient’s chest. The first stethoscope resembled a cylinder, was made from wood, and was monaural (only one ear could be used to listen to the patient’s chest).

Since the 19th century, the stethoscope’s design has evolved to become the lighter, more flexible, and binaural version we are familiar with today. Nowadays, doctors can even opt for either the traditional acoustic stethoscope (consisting of a hollow tube that transmits acoustic sound waves from the patient’s body to the doctor’s ears) or the electronic stethoscope (converts sound waves into electrical signals). An advantage of the electronic stethoscope is its ability to amplify quiet components of sounds from a patient’s body.

Left: Laennec’s original stethoscope © Science Museum, London. Right: A modern Littmann stethoscope © Medisave UK Ltd

X-ray machines

X-rays are a form of electromagnetic radiations that were discovered by accident – the German Physics professor Wilhelm Röntgen was conducting experiments on cathode ray tubes when he noticed the emission of this new form of radiation. After further experiments, Röntgen used these novel rays to create an image that would forever change the course medical diagnosis – an X-ray photograph of his wife Bertha’s hand.

Since their accidental discovery in 1895, X-rays have been widely used in clinical settings to detect foreign objects in the body (like swallowed coins) and visualize internal parts of the human body. First-generation medical X-ray machines produced blurred images and required a 90-minute skin exposure time to the radiations. In contrast, modern X-ray machines take high-resolution images after a skin exposure time of merely 21 milliseconds, with the radiation dose to the skin being 1,500 times lower. Nowadays, it is possible to even attain three-dimensional, coloured images of soft tissues and other body parts.

Images of the hand specimen of an 86-year-old woman obtained with a first-generation X-ray machine about a 100 years old (left) and a modern x-ray system (right).
Left, the first X-ray ever made of Roentgen’s wife’s hand in 1895. Right, a cone-beam CT 3-D reconstruction of a hand in 2015 using a new robotic digital radiography (DR) X-ray system.

Artificial cardiac pacemaker

An artificial cardiac pacemaker is a device used to produce electrical signals that cause the heart muscle to contract and pump blood. It is indicated for patients with dysfunctional electrical activity in the heart. Over the past century, artificial cardiac pacemakers underwent tremendous evolutionary changes to become the devices we know today.

The first “artificial pacemaker”, invented by Albert Hyman in 1932, consisted of a spring-wound, hand-cranked motor which produced and directed electrical impulses to the patient’s heart through a needle electrode. Since then, the artificial cardiac pacemaker evolved into an external, table-top electronic device tethered to an extension cord; a battery-operated wearable device; and totally implantable device. Further advancements in pacemaker technology like leadless pacemakers and ability to stimulate the heart’s lower chambers (ventricles) simultaneously have greatly improved cardiac symptoms and overall survival.

Early external electronic pacemakers
Wearable cardiac pacemaker

Electrocardiogram (ECG) devices

ECG devices record electrical impulses traveling through the muscles of the heart chambers. These recordings appear as waves on a moving strip of paper or digitally on a screen. Dutch physiologist Dr Willem Einthoven invented the first electrocardiograph in 1902, paving the way for dramatic improvements in cardiac disease diagnosis.

The evolution of ECG devices is a testament of how technological advancements can be leveraged to create more accurate and convenient versions of the same device. Dr Einhoven’s electrocardiograph occupied an entire room and weighed around a whopping 300 kilograms. The first portable ECG machine in the late 1920s was battery-powered and weighed around 20 kilograms. Modern transistor- and microchip-related technologies were leveraged to produce the modern 12-lead ECG devices we know today. And nowadays, cutting-edge ECG devices have electrodes that weigh merely 18 grams. Devices like AliveCor’s KardiaMobile capture medical-grade ECGs in seconds from the comfort of your home and with minimal effort. These readings can then be viewed on a smartphone and easily shared with doctors.

The ability to detect serious heart arrhythmia using mobile technology has the potential to save lives, reduce healthcare costs and allow patients and doctors to make informed decisions about cardiac care. You can monitor your heart health in check from the comfort of your home, in just 30 seconds. This path-breaking technology was granted FDA-clearance for its algorithm to detect atrial fibrillation (AFib), the most common form of cardiac arrhythmia.

The first electrocardiograph
AliveCor’s kardia Mobile Product


#1. The X-ray was discovered after years of planned research.

#2. Pacemakers used to be a table-top device before they were implanted in the body.

#3. ECGs record electrical impulses.

#4. A stethoscope can be used to listen to breathing.