16-06-2022 | By Robin Mitchell

Researchers from Northwestern University recently developed a small temporary pacemaker that dissolves safely inside the human body when no longer needed. What challenges do implanted medical devices present, what did the researchers achieve, and how can such devices aid medical care in the future?

What challenges do implanted medical devices face?

Engineers have been able to develop devices to withstand all kinds of environments, whether in the furthest reaches of space, the heat of a forge, the corrosive air of the sea, or the extreme pressure at the bottom of the ocean. But when it comes to the human body, trying to develop a device designed for implantation presents a multitude of challenges that are unique to living tissue.

The biggest challenge by far is that living tissue is extremely sensitive to foreign bodies. A good example of this is how the human body reacts to a wooden splinter. The immune system detects the presence of the splinter and results in the formation of puss around the splinter. This response is to try and kill off any potential pathogens and break down the foreign body. However, wooden splinters are not easily dissolved, and this can result in inflammation, soreness, and infection.

As such, any device that is to be implanted must be biologically inert, meaning that it will not cause an immune system response (i.e., go unnoticed). To make a device biologically inert, it has to be made of carefully selected materials that are unreactive (such as glass and titanium).

The second challenge is that any device implanted in living tissue must be made from non-toxic compounds that will not pose a serious risk if damaged. This is particularly an issue for batteries as most battery technologies contain harmful compounds.

The third challenge is that implanted medical devices that plan on being used for a short period will need surgery to install and remove. Repeated surgeries not only present discomfort to the patient but also carries the risk of infection and damage to internal organs and tissue.

Researchers develop implantable pacemaker with sensors that degrade after use

Recognising the challenges patients face when implanting medical devices, researchers from Northwestern University have announced the development of a pacemaker that not only integrates sensing capabilities but also dissolves safely after use.

Instead of integrating a power source onto the pacemaker device, it utilises conductive traces that form an antenna, and a chest-worn device transmits power to the pacemaker wirelessly. Additionally, the use of an antenna and carefully designed traces allows for the chest-worn device to also infer bioactivity with the aid of neural networks. Data that the system collects include heart rate, body temperature, oxygen levels, respiration, and muscle tone, which is used to determine the condition of the heart.

Furthermore, the researchers also demonstrated how the implanted sensor can fully dissolve in human tissue without causing any rejection from the immune system. This means that the temporary device will dissolve after several days of use (day 40 shows the sensor having completely disappeared). The sensor can also be connected to a smartphone over Bluetooth for patient monitoring and provide alerts should the pacemaker fail or detect an anomaly.

How can such devices aid medical care in the future?

One of the most significant advantages of such a device is that it helps to provide patients with an element of freedom by removing the need for wires. A heart patient fitted with such a pacemaker could recover in the comfort of their own home instead of taking up hospital space. By keeping patients away from hospitals, they also reduce the risk of secondary infection, which can be seriously dangerous for patients with weak hearts.

The researchers also noted that their device could be ideal for newborns suffering from heart defects, including holes between chambers. As these conditions will often heal themselves over time, the only need for the newborn is to have a pacemaker that regulates cardiac rhythm until the hole is sealed. As such, using the temporary implanted pacemaker makes perfect sense as it will provide the pacemaker needs for a short time before dissolving safely.


By Robin Mitchell

Robin Mitchell is an electronic engineer who has been involved in electronics since the age of 13. After completing a BEng at the University of Warwick, Robin moved into the field of online content creation, developing articles, news pieces, and projects aimed at professionals and makers alike. Currently, Robin runs a small electronics business, MitchElectronics, which produces educational kits and resources.