Solid State Battery as implant power source

Hello,

I’m working on a project where I’m trying to collect vital signs for emergency case monitors. Here is the webpage with some information on it:

Angels Guard

This idea can be utilized in many applications, like baby monitoring or senior vital sign monitoring to name just a few. One idea is to use implanted sensors to collect vital signs which than can be requested via NFC I2C interface The main issue is the problem with the power source for such devices. I found solid state batteries what appearing as perfect candidates for the use in implants.

coin_shot

Here is a link to the company which makes those chips:

Home of the World’s Smallest Solid-State Batteries - Cymbet

The fact that those chips are available in Die form makes them good candidates for implants. It’s probably possible to build a implantable ECG sensor by using a LPC8N04 MCU from NXP and those SSB’s by sandwiching those chips together.

stackdie

I was wondering if anyone has ever played around with those chips?

It’s possible but the energy density is so bad that you’d have to probably make your own custom silicon die design to maximize power efficiency and not waste cpu cycles or RF packets on anything but exactly your intended application.

… oh and you’d probably have to forgo any sense of security or cryptographic protections… raw analog data transmission is very likely what you’d have the power budget for and nothing else.

@amal You’re correct the power density of those solid state battery chips is very low, but it’s only used to collect data. The transmission part is done when the NFC transmitter is powering the MCU and this will provide enough energy to run any kind of security protocol if this is necessary. The LPC8N04 MCU from NXP comes only in one packaging form which would be somewhat to big for an implant. NXP offers the NHS3100 in WLCSP25 packaging with dimensions of 2.51mm × 2.51mm × 0.5mm and you can even get it as bumped die which has the same dimensions but it’s only 0.16mm thick. The latter version would open the possibility to sandwich it together with the solid state battery chip.
This construction could build the base for a host of datalogging sensor solutions in form of implants. One example could be the MAX30003CWV+T from Maxim Integrated, which is a Ultra-Low Power, Single-Channel Integrated Biopotential (ECG, R-to-R Detection) AFE. An implanted ECG would be possible with that chip.

Fun! 2 lead I would imagine, and necessary to be directly over the heart… what would the minimum length be to get enough differential between probes?

If the power density of that thing is that low, isn’t it essentially just a paper capacitor?

The advantage presumably is the much lower leakage current. In short, able to hold a charge a lot longer so the electrons can do work instead of sneaking through your electrolyte

Yeah but…

I was talking about non-electrolytic capacitors (paper, mica, ceramic). Those should have such negligible leakage as to be impossible to measure.

They also have a pretty shoddy energy density. Hence the comparison with that solid state battery thing: it sounds to me like a basic dry capacitor with a lot of marketing attached.

You guy’s are correct the energy density of those chips is extreme low and probably not enough to power anything long enough to collect data. The MAX30003CWV+T as analog front end is very need. I experimented around with those devises somewhat and it delivers usable results with astonishing primitive conditions. Two electrodes the size of a dime about two inch apart are enough to get usable results and the heart rate detection is already build in which means one don’t need to waste time with implementing it into the μController. Now, I’m not sure how implanted electrodes will work with it, but it only can get better.

With capacities of 5uAh, 15uAh, 50uAh you could honestly use a couple dry capacitors and piezo energy harvesting to get the same effect, and it wouldn’t run out.

You’re right, there’s always other ways to do something with the same outcome, but this isn’t the point. Those chips are ideal to build custom chips by stacking them up with each other and this is something you can’t do with a couple of dry capacitors. Also, the size would be interesting compared to the capacitor version.

You lost me here, can you explain how exactly you want to make this work in an implant?

Currently it’s mostly used for pacemakers but there are other potential applications. I’m just saying your talking about so little energy that it could be acquired through various energy harvesting methods that are already available, then you wouldn’t have to worry about replacing the batteries or recharging them with the application of an external field. My opinion is that batteries would only ever be worth implanting for higher power density applications that can’t be accomplished by any other means.

Those examples you’re talking about are pure experimental and far from any actual practical application. The idea is to use piezo elements to generate electricity from mechanical movement. You’re aware that there’s nothing on the market what is able to harvest enough energy to charge a battery of some sort, in form of an implant. However, its much more faceable to recharge any implanted battery inductive similar we already doing with our phones. The advantage of the solid state battery chips is that no current limiting circuit is necessary which simplifies the implant significant. The other advantage of those chips is their low energy density prevents overheating which is an important factor in implants.

Yup, you’re right. Sorry, I’m not trying to attack your idea, I was just pointing out some other options that have been considered. Is it possible to get samples of these chip scale batteries? I’ve seen a lot of examples of ideal power sources for implants like betavoltaics and piezo energy harvesting, but they either fall through because the manufacturer stretched the truth on their progress to market or they only allow minimum order quantities of 1 million units.