HELP:Dealing with Diabetes Project

[LeungWilley]

Hi,
Sorry for the delayed response.
With the Digital multi-meter, we are going to be taking measurements at different points of the circuit to see if we can identify what's wrong. Specifically, we will be using the circuit diagram at the "HELP" section as the basis of these tests. https://www.sciencebuddies.org/science- ... creas#help

To start, let's confirm that the 12V is getting to the circuit board.
1. Set you meter to read DC Voltage and apply the leads. The black lead should be attached to the BLUE rail, and Red lead should be attached to the Red Rail. If everything is working, you should have 12V on the meter.

2, The next place to measure is the voltage divider, Vout of Figure 14. Leaving the black lead in place, connect the lead to the resistor leg on 1C (or add a wire at 1D so that you can clip on to it.) This should read the Vout that you calculated using the equation. (It should be around 3V)

3. If this checks out, the next point to measure is the gate voltage at the transistor (after the conductivity sensor). Again, keeping the black lead at the same place, measure the voltage at row 7. (You can move the wire from 1D over to 7D if that makes getting the reading easier.) This is the VGS mentioned in the help file. When VGS is greater than Vth, then the pump should run. Please measure what this voltage and if it is less than Vth, please, adjust the potentiometer and see if you can bring up the voltage.

Hopefully, this should solve the problem. If not, please post again with your results and we can see what else may be going on.

Good Luck and Have a great Holiday!
Willey

[bahelan23]

I just have one more question. Do you think that the MOSFET has something to with our circuit not working.
Hope you also have a wonderful holiday.

[LeungWilley]

Hi,
Yes, the MOSFET is most likely the problem if all of the voltages are as expected. (Out of all of the components on the board, it is the component most susceptible to damages.)

Willey

[bahelan23]

Then if the MOSFET is the problem what would we have to do to fix it.

[LeungWilley]

It would have to be replaced with a new part.
(Unfortunately, there's nothing we can do to repair it)
Willey

[bahelan23]

When you say new part, do you mean a new MOSFET or something else.

[LeungWilley]

Yes, new MOSFET.

[bahelan23]

We tested with the multi meter and tests one and two seem find, but step three there was no reading. We are going to test step three again when we make the solution.

[LeungWilley]

Ok, good luck!

[bahelan23]

For this project, I was just wondering, where would we put this device in a human body. Also, I will follow up with my results.

[LeungWilley]

Hi,
With our current technology, I don't think we will be putting this device inside a human body any time soon.
Here's the one of the latest article on its current development:
https://tcoyd.org/2018/02/the-artificia ... it-coming/

More than likely, at least in the initial phase, this will be an external device so that you can power the pump and resupply the insulin as needed.

Willey

[bahelan23]

Would this be a device that would, externally, be connected to our body and the pup tubes internally.

[bahelan23]

Also, in the article it said that the third component would be a device such as a phone to direct the insulin. What in our project directs insulin. Are we doing this manually?

[LeungWilley]

In this project, the conductivity sensor is what controls the pump, please refer to Figure 4 in the background section. If the solution is conductive, the pump is turned on. If not, the pump is off.

Instead of just simple on/ off, the third component (Phone / Computer) mentioned in the article will allows you to do things like "pre-pump" the system before a meal or having the ability to predict what the blood sugar level might be after exercise, etc...

And yes, I am guessing people will wear this device on a belt with tubes connections to blood sensor and insulin injection site.

Willey

[bahelan23]

Thank you! I appreciate it.