Interview with Steven Hackworth

Steven Hackworth is a Ph.D candidate at the University of Pittsburgh who worked on the DBS-RF (a wireless deep brain stimulator) as well as the Radio Frequency-powered Neural Stimulator (RFNS) vagus nerve stimulator system. He's now doing research on energy sources and medical implants. After writing about RFID in neurotech the other day (a prequisite to this post, many links there) I did a brief email interview to follow up.

Are the DBS and VNS RFID systems using the same principle or technique or were there unique challenges for the two types of devices? I'm wondering how portable the technology is to other neurostimulation and medical devices, essentially.

The DBS and VNS systems do use the same RF technology. Magnetic inductive coupling is used for powering and communication. There are two major differences between the devices though: 1) The DBS device uses voltage pulses while the VNS device controls current injection. It was just a matter of modifying the circuitry on the output side to adapt the DBS device for VNS. 2) The implementation of each device must be different. i.e. the DBS device is under the scalp, requiring an external powering unit on the head, while the VNS device is located in the neck, requiring an external powering unit in a person's collar or similar. Though I did develop an example of a powering system (with the primary coil in a hat), this issue wasn't investigated thoroughly, and would be left to a company to come up with a suitable implementation (is a person supposed to wear a bag on his head whenever he takes a shower? ... etc.). Back to the essence of the question, the same fundamental RF technology should be transferable to other neural devices.

How do the systems ward against RF interference [thanks BGP for that question], and potential hackers? Is there a designated frequency for medical devices, different from retail RFID and such?

The inductive coupling mechanism used has a fairly short range. Depending on the system, it might be up to a foot, but practically, you don't want to blast people with RF energy. The current systems for DBS do in fact use RF communication for programming (Medtronic's system for Parkinson's, at least), but the user on/off switch is controlled by a magnet, making it susceptible to magnetic interference. Using an established protocol to turn the device on or off would guard against unwanted toggling. I think Medtronic's newer systems may be implementing this, as I've seen newer designs for the patients' controllers, but I can't say for sure. Regarding hackers, I doubt that is an issue. I haven't heard of any malicious cases
with the current easily controlled systems, so I doubt if anyone would go to the length to figure out the communication protocol and turn people's stimulators on or off. The reason for the protocol is to keep the probability of unwanted interference negligible (just like wireless internet and cell phone protocols).

The frequencies used fall into the FCC-designated ISM bands. Industrial, Scientific, and Medical. Anyone can use these frequencies, as long as they abide by certain rules and regulations. There are fairly standard frequencies used for RFID systems, and medical devices could use those or others, as long as they abide by FCC regulations.

In your current research with energy to implants, what are the main challenges (in a nutshell), and promising developments? (i.e. New types of batteries, other energy sources? What about using the body as an energy source, is that feasible?)

The main challenge involved with getting energy into the body is getting through the body itself. It is highly conductive, and conductive layers tend to block any sort of electro-magnetic signals.

However, we are doing research on using those conductive properties to actually transfer signals instead of acting as a barrier. We are also looking into what we can do to modify tissue properties to increase energy transfer efficiency. As mentioned earlier, practical implementations of the technology will be an issue. There is some research into harvesting energy from the body. Though still in its infancy, it looks ever more promising as technology improves and requires less power.

Thank you Steven!

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Tags: neurotech RFID research implants science technology futurism