Category Archives: energy harvesting

Injectable Electronics: dawn of a new era in electroceuticals?

Injectable electronics still need to become smaller

Frequent readers of this weblog may still remember a previous post, entitled “And the paralyzed will walk again“. This phrase comes from a Discovery Channel movie/documentary, called “2057: the body”, in which it is predicted that by the year 2057 you will be able to survive a three story fall and even be able to walk again as there will be tiny microstimulators attached to your muscles, which can be injected.

Injectable electronics, how fascinating would that be! No more lengthy surgeries, during which only a single, bulky device is implanted, but rather a procedure that takes less than a couple of minutes, during which multiple micro-stimulators are inserted via a seringe. Once done, these stimulators will form a wireless network and will provide the motory neural pathway with well-timed electric stimuli necessary to evoke the correct contraction of the multiple muscles involved in a delicate movement or even seemingly simple posture control.

But how feasible is this idea of injectable electronics? If you search for the term injectable electronics, you will most likely find a lot of references to the work of John Rogers, professor at the University of Illinois in the US, who built “an electronic LED device so tiny it can be injected into delicate tissue, such as in the brain, without harming it“.
Other links that can be found refer to work done on silk implants or even magnesium implants that are either stretchable or can easily dissolve into the body once the good work has been done.

I personally believe that we only can create injectable electronic devices if they have at least some intelligence in them. For this, the good old silicon would be an excellent candidate. Silicon is a nice and friendly biocompatible material, can be made bendable (by thinning the substrate) or stretchable (by removing the substrate altogether at some points). And what’s more, silicon can accommodate stimulation circuitry, sensors, signal processing, communication electronics, antennas, battery foils, all the good stuff needed to make a good injectable.

Of course, in order not to damage the tissue that the electronic device is injected in, it needs to be small, i.e., thin and narrow. It is however allowed to make it long, e.g., a couple of millimeters up to one or two centimeters. These unconventional dimensions raise very exciting technological challenges, such as:

  • how can we create electronic integrated circuits (ICs) that are merely one-dimensional, i.e., are not wider than one, maximally two, bondpads?
  • how can we transfer information and energy to an implant that has virtually no area?
  • what kind of material should we use for the antenna and electrodes?
  • will a Li-Ion battery foil have enough capacity to provide successful stimulation of the tissue, or should we refrain from using batteries altogether?

There obviously is still a lot to do. Exciting stimes ahead, if you ask me.

Wouter

A new name, but Biomedical Electronic remains

Biomedical Electronics Lab

Dear Reader,

The Biomedical Electronics Group underwent a small name change. From now onwards, the group is called “The Biomedical Electronics Laboratory”.

Its mission is “to provide the technology for the successful monitoring, diagnosis and treatment of cortical, neural, cardiac and muscular disorders by means of electroceuticals.”

To this end it conducts research on, provides education in and helps creating new businesses in neuroprosthetics, biosignal conditioning / detection, transcutaneous wireless communication, power management, energy harvesting and bioinspired circuits and systems.

Can heart beats really power cardiac pacemakers?

Baron von Munchausen

Today, I received a link (http://tweakers.net/nieuws/85353/hartslag-kan-pacemaker-van-stroom-voorzien.html) from Marijn, honorary member of the Biomedical Electronics Group, in which it is mentioned that researchers have found a way to harvest enough energy from a piezo-electric transducer so that a cardiac pacemaker can be powered from the heart itself. This would render the bulky batteries in the pacemakers unnecessary and the pacemaker thus does not have to be replaced after a couple of years because of a depleted battery.

I have two concerns about this. First, there is a kind of “Baron-von-Munchausen” effect. Baron von Munchausen was an 18th-century German nobleman, who, according to Rudolf Erich Raspe’s story The Surprising Adventures of Baron Munchausen, pulls himself out of a swamp by his hair (specifically, his pigtail). Now, let’s suppose that a pacemaker, equipped with a piezo-electric energy harvester to power the pacemaker, for no particular reason, fails to operate and the heart stops its precious beating, what will then power up the pacemaker again to make the beat again? Scary thought, isn’t it?

Second concern is of another nature. Pacemakers are usually replaced, not because the battery has depleted, but simply because a next generation pacemaker can provide a better therapy to the patient. As a side note, uncomfortable but true, current pacemakers (and thus also the batteries included therein) on average live longer than their owners. Hopefully this latter aspect will change for the better soon.

Wouter

Mission Possible

In order to present the Biomedical Electronics Group of Delft University of Technology to a couple of companies, it made sense to reveal our mission statement. So here it goes…

The mission of the Biomedical Electronics Group of Delft University of Technology is "to provide the technology for the successful monitoring, diagnosis and treatment of cortical, neural, cardiac and muscular disorders by means of electricity." In order to reach this goal we investigate and design circuits and systems for electrical stimulation, ExG readout, signal specific analog signal processing, power management/conversion, energy harvesting and wireless communication, to be applied in future wearable and implantable medical devices, such as hearing instruments, cardiac pacemakers, cochlear implants and neurostimulators.

So how about that? Reactions are welcome via this blog.

Wouter