Real Time Continuous Blood Monitoring | Hacker News Reader

Real Time Continuous Blood Monitoring

news.stanford.edu

121 pointsKukiAirani25 comments

The paper A fluorescence sandwich immunoassay for the real-time continuous detection of glucose and insulin in live animals [1]:

> Here we show that multiple analytes can be continuously and simultaneously measured with picomolar sensitivity and sub-second resolution via the integration of aptamers and antibodies into a bead-based fluorescence sandwich immunoassay implemented in a custom microfluidic chip. After an incubation time of 30 s, bead fluorescence is measured using a high-speed camera under spatially multiplexed two-colour laser illumination.

> Incoming beads are first illuminated by a red laser, which interrogates the Cy5 fluorescence intensity indicating the glucose concentration. This is followed by illumination with a green laser that interrogates the R-PE fluorescence intensity, which measures the insulin concentration. We used an exposure time of 50 ms and acquired images every 100 ms.

> To allow for real-time analysis, RT-ELISA requires a continuous supply of reagents, which corresponds to approximately US$10.50 worth of reagents consumed for a 1-h run.

> The detection scheme will also need to be miniaturized to reduce its complexity, most notably with regard to the camera and other optical components. However, we believe that such miniaturization would be possible with integrated photonics and that further advances in these technologies could make RT-ELISA suitable for bedside patient monitoring.

[1] https://www.nature.com/articles/s41551-020-00661-1

I'd love to get one of these. I have been using a whoop to sanity check all my exercise routines with their recovery data. I feel like something like this could help me hone in on the perfect diet and lifestyle even better than a continuous glucose monitor.

What's a whoop?

Looks like it is a fitness tracker of some sort.

https://www.whoop.com/

It’s a smartband or more like https://www.aidlab.com ?

It's a heartrate wearable that focuses on really accurate heartrate variability measurement. This is important as it's an indicator of recovery.

This is the only article I could find that includes detailed information comparing the Whoops sensors to other devices: https://www.dcrainmaker.com/2020/05/whoop-3-platform-review....

Do you happen to know of others?

I don't have an article about it, but the reason i chose to replace my apple watch with a whoop was because i wanted insight into my HRV. Apple watch only measures HRV a few times a day, while whoop is continuous. I would only recommend a whoop if you are concerned you might be overtraining, that's what i use it for.

You might not be getting accurate recovery data from Whoop. The heart rate sensor is doesn't work very well. https://www.dcrainmaker.com/2020/05/whoop-3-platform-review....

Data has been pretty close to my Apple watch. One annoying part is it sometimes stops transmitting data to my bike computer, but I think that’s a Bluetooth problem and after the workout I will check the whoop app and it was recording the whole time.

Can somebody please explain the challenges associated with miniaturizing and speeding up the ELISA test?

On wiki [0] I see:

> In the most simple form of an ELISA, antigens from the sample to be tested are attached to a surface. Then, a matching antibody is applied over the surface so it can bind the antigen. This antibody is linked to an enzyme and then any unbound antibodies are removed. In the final step, a substance containing the enzyme's substrate is added. If there was binding the subsequent reaction produces a detectable signal, most commonly a color change.

What are the pain points in this process?

[0] https://en.wikipedia.org/wiki/ELISA

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5325810/

The big game changer for these microfludic ELISA chips is the increased surface area / volume ratio. While this can speed up incubation quite a bit, you can also run into problems at low concentrations of where (1) you can start depleting the sample, and (2) mass action kinetics no longer apply.

Also figuring out how to reliably manufacture these to within a certain tolerance is a very difficult feat of engineering.

I haven’t been active in this field for a while though, so these may no longer be issues.

Fascinating. Sounds like it would change a lot of the diagnostic tools for blood tests. Fingers crossed it works as easy as the document says and they can get a good price to market!

It would probably be really important miniaturize this as much as possible to reduce reagent costs. Primary/secondary antibodies are not cheap.

It’s cool to see a real lab-on-a-chip that works. I remember reading about these in college over a decade ago, and while they always seemed “cool” from an aesthetic standpoint, there was always a question of what could you actually do with it (i.e. how is the chip better than just basically mixing things in a test tube + centrifuge).

This is interesting but it's still invasive to the extent that it requires a blood sample. I think it would be very useful if it were possible to do some form of in vivo spectroscopy, probably either IR or NMR.

Does anyone know of any work being done in this area and what the challenges are ?

Whoa, this is really interesting...

This feels like the dream of Theranos that people fell in love with.

Sounds like what https://www.levelshealth.com/ is doing

Completely different technology and completely different use case...

It would be cool to have an interstitial fluid version of something like this although. IF contains all sorts of stuff, like ketones, hormones, cortisol and more and is less invasive to measure than direct blood. It would be pretty awesome to have a generic biomonitor that monitored all of this. It would probably be amazing for athletes and scientific health studies.

"Interstitial fluid consists of a water solvent containing sugars, salts, fatty acids, amino acids, coenzymes, hormones, neurotransmitters, white blood cells and cell waste-products."

https://en.wikipedia.org/wiki/Extracellular_fluid#Interstiti...

Also https://www.veristable.com/

Isn't that very similar to what Theranos was supposed to be doing?

I would have to expect there were at least a few brilliant scientists who worked there and contributed some momentum in this direction, and could be regaining some footing in legitimate operations now.

Theranos was claiming they were already delivering the full spectrum of tests when the promise is still not fullfillable.

Alternatively, realistically focusing on a single miniaturized test or two until you get consistency with the established reference instruments could provide the foundation for a worthwhile investment by comparison.

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