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Blood is thicker than water

A project log for Open source Arduino blood glucose meter shield

Open hardware and software blood glucose meter using electrochemical test strips

m-bindhammerM. Bindhammer 06/12/2016 at 12:516 Comments

Today I tested the commercial ONETOUCH ULTRA 2 blood glucose meter. I prepared a solution of 100mg D-(+)-Glucose/dL distilled water to test the meter. But the meter didn't recognize the aqueous glucose solution. Always the same ERROR 4 occurred:

Obviously the electrochemical process does not start with a pure aqueous glucose solution. I tried to prepare some kind of artificial blood by adding 1g potassium ferricyanide to the glucose solution. Now I got readings, but much lower than the actual glucose concentration of the solution:

Update:

According to the suggestion of Ryan Bailey I prepared a solution of 0.9g NaCl and 100mg glucose per 100ml distilled water. Result again ERROR 4:

I think the reason why potassium ferricyanide worked in the test solution is because potassium ferricyanide is used in many amperometric biosensors as an electron transfer agent replacing an enzyme's natural electron transfer agent such as oxygen as with the enzyme glucose oxidase. Potassium ferricyanide is also used as a blood replacement and catalyst for the chemiluminescence demonstration of luminol.

Next step: I will try to analyze the glucometer calibration solution.

The ONE TOUCH ULTRA control solution has a blood-red color. No ingredients are mentioned on the bottle. On the instruction leaflet is mentioned that the control solution consists of glucose in water (about 0.11%) with buffers and stabilizers, a viscosity adjusting agent, a preservative, and a red dye.

The glucose meter shows a concentration of 135mg glucose/dl.


Discussions

داستایُبس.کی wrote 08/31/2020 at 08:19 point

i used a EASY Gluco device for my papers.there is a Control Solution vial in its bag...can i calibrate my results with this vial?

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Tom Meehan wrote 06/14/2016 at 01:21 point

If you want to save some time and headaches just purchase some bG meter control solutions (most drug stores and even Walmart carry them).  They are designed to be used with bG test strips to ensure that the meter is calibrated correctly. Price ranges from about 3 - 8 dollars for an eye dropper sized bottle.

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M. Bindhammer wrote 06/14/2016 at 06:16 point

Hi Tom,

Thanks for the follow and like. I purchased already a glucometer calibration solution. Intersting would be calibration solutions with different concentrations, that's why I am also want to synthesize test fluids by myself.

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Ryan Bailey wrote 06/13/2016 at 20:14 point

Awesome. I look forward to hearing how it goes. I should correct my earlier comment: 0.9% normal saline is 9g/L, not 90g/L.

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M. Bindhammer wrote 06/12/2016 at 21:13 point

Thanks, Ryan. Just bought the glucometer calibration solution. And will also try to use a NaCl/glucose solution.

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Ryan Bailey wrote 06/12/2016 at 20:46 point

I think you're on the right track by adding some potassium - the test is going to be very sensitive to the electrolyte content of your test fluid (blood is quite salty, after all), hence why you got a better reading by adding some K+. Potassium is one of many electrolytes found in normal blood but definitely not the dominant extracellular one (Na+). You might try adding some NaCl targeting the normal serum osmolarity of 275-295 mOsm/L. I suggest mixing up some normal saline (isotonic fluid often used in hospitals), which is 0.9% - or about 90g/L NaCl solution. Then add your glucose and see what happens.

Another possibility would be to try a glucometer calibration solution - most meter manufacturers sell one. For example: https://www.amazon.com/OneTouch-Ultra-Control-Solution-Vials/dp/B0000532FC/

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