Author Archives: Wouter Serdijn

Cell phones affect the glucose concentration in the brain close to the antenna

The Journal of the American Medical Association will soon publish an article on the effects of the use of a cell phone on the glucose concentration in the region of the brain close to the antenna. According to the Preliminary Communication published today, the brain cells exposed to 50 minutes of radiation from the cell phone had a significant increase in their glucose metabolism of about 7 percent. Its clinical significance, however, is yet unknown.

Though I understand the clinical study conducted and the scientific method applied, there are some comments that I would like to vent.

The first one is about the state of the mobile phones used. The article mentions that they were on for 50 minutes. But what does "on" mean exactly? Were they just on standby, waiting for a call? Was a call being made? If so, for how long? Was there any data passed between the cell phone and its base station? But the total "talk time", or better, transmission time, is not revealed in the article.

Moreover, its is known that the amount of power transmitted by the cell phone depends on the distance to the base station. Fortunately, the cell phone decreases its output power when channel conditions are good enough, thereby extending its talk time and reducing co-channel interference. This thus implies that the amount of radiated power is another unknown in this study.

Finally, and this becomes evident from a literature study and experiments conducted by our own Mark Stoopman, the amount of energy being absorbed by brain tissue strongly depends on the frequency being used. This, in turn, depends on the type of service (GSM, UMTS, etc.) and the provider being used. GSM 1800, for instance, in use by, e.g., T-Mobile, leads to more tissue absorption than GSM 900.

All-in-all, a lot of unknows, if you ask me.

Wouter

Would you allow your brain to drive your car?

German scientists have managed to develop a car that can be controlled by signals recorded from the brain. These signals are captured by a brain interface based on electro-encephalography (EEG) sensors, which was originally designed for gaming.

  

Click here for a video that highlights the thought-powered driving system on a trip to the airport. More information on the BrainDriver can be found here.

Currently, the system still experiences serious latency, as the brain waves first have to be analyzed, clustered and classified — I’d recommend a multi-wavelet transform for doing so — before appropriate action can be taken. It still will take a while before we really can take our hands off the wheel, sit back and imagine we’re at our destination already.

Are we all cyborgs now?

Check it out for yourself at TED.com, in this inspiring talk by Amber Case. Keep an eye on your self, though.

TED logo

Another one, highly recommended, is by Oliver Sacks, the famous neurologist and author (e.g., of the book Musicophilia). In this presentation, he points out an interesting link between visual hallucinations and tinnitus. Click here.

Can the upcoming solar storm turn your pacemaker into a killer inside you?

It has been predicted that today (Febr. 17, 2011) one of the largest solar storms in years will reach the earth and may interfere with sensitive electronic equipment, such as GPS receivers in cars and PDAs. Also air traffic and power grids may suffer from this kind of interference.

 Solar Storm 

Solar storms, also called geomagnetic storms, are caused by solar coronal mass ejections and modify the electromagnetic fields in the ionosphere, magnetosphere and heliosphere. They usually last only one or two days and can cause auroras further away from the poles than usually. According to Wikipedia, "On March 13, 1989 a severe geomagnetic storm caused the collapse of the Hydro-Québec power grid in a matter of seconds as equipment protection relays tripped in a cascading sequence of events. Six million people were left without power for nine hours, with significant economic loss."

So how dangerous are these solar storms for life-supporting devices like pacemakers and neurostimulators? In order to answer this question, we need to understand the physical and electrical effects of solar storms. Solar storms induce fluctuations in the Earth’s magnetic field. These fluctuations, in turn, can induce currents in large electrically conducting structures, such as power grids and metal pipelines, leading to damaged transformers and corrosion. Solar storms also influence the electrical currents in the magnetosphere and the ionosphere and thereby affect wireless communication that propagates through them.

So my conclusion: as long as you do not use your shortwave radio or CB set to control your implantable device remotely and you do not power it from the mains, you’re safe. Ain’t that a relief?

Wouter

Electric stimulation turns geek into sex god

"Electrical stimulation of certain hypothalamic regions in cats and rodents can elicit attack behaviour," is what we can read in Nature today. But also "Neurons activated during attack are inhibited during mating, suggesting a potential neural substrate for competition between these opponent social behaviours." If the same holds for human beings, which is highly probable, then we are not far away from the situation in which we can replace Cialis by a healthy dosis of instant neurostimulation or switch the neurostimulator to Arousal Mode No. 2 to beat the guy that left the bar with another one’s girlfriend. As long as they do not take my Erdinger, I’m fine.

Jokes aside, it is known that both regions in the brain are closely located to one another, together with the part that controls voluntary urination. So my advice: don’t try this at home.

Li-Ion batteries on silicon come to the rescue

Yesterday, Erik Kelder (NSM group, TU Delft) explained us how thin-film microbatteries can be made in silicon. These batteries seem to be naturally suited for the next generation of implantable neurostimulators. Read more about the newly initiated FP7 project at: http://www.tudelft.nl/live/pagina.jsp?id=39d5ebc3-7ec3-4b26-a298-058bb5f8a24c&lang=en

How to detect the right information from the brain to see a seizure coming?

It looks like the best way to detect the onset of an epileptic insult is by doing a wavelet transform on the acquired ECoG. However, which morphological features to look at is far from trivial. For the first generation of closed-loop neurostimulators it is therefore probably best to acquire the complete ECoG signal at full resolution and do the morphological analysis in the digital domain entirely. In a later phase, the (analog) frontend (sense amplifier) can be made more specific, thereby releasing the burden from the analog-to-digital converter and the signal processing in the digital domain.

SINS meeting today!

Today, we will have a meeting of the SINS program and its international consortium. In this meeting we discuss new directions in neurostimulation and -modulation, bladder stimulation for urge incontinence, new technologies for Li-Ion battery foils, implantable electrodes in silicon, neuroscience on mice, closed-loop neurostimulator operation and tinnitus. I look forward to an exciting day…

Wouter

The Biomedical Electronics Group

The Biomedical Electronics Group

The Biomedical Electronics group anno 2010. From left to right:

Rachit Mohan, Gaurav Mishra, Wu Chi Wing, Yongjia Li, Wouter Serdijn, Duan Zhao, Robin van Eijk, Chutham Sawigun, Mark Stoopman, Hossein Tajeddin, Vincent Bleeker, Wannaya Ngamkham, Menno Vastenholt, Senad Hiseni, Cees-Jeroen Bes.

Not on the photo: Andre Mansano, Sumit Bagga, Marijn van Dongen, Hamed Aminzadeh, Marcel van der Horst, Yixiong Hu

Picture taken by Unknown, 2010

Moving diagnostic, monitoring and therapeutic wireless medical devices into the homes and into the body

== Invited presentation by Wouter Serdijn at ISMICT 2011 on “Moving diagnostic, monitoring and therapeutic wireless medical devices into the homes and into the body”, Montreux, Switzerland, March 30.