Solved: Does the LPS33HW contaminate water? - STMicroelectronics Community

I am trying to develop a smart tumbler.

Smart tumbler measures the amount of water you drink per day.

Place LPS33HW on the bottom of the tumbler and measure the amount in water.

I think the LPS33HW should come in contact with water.

Water is eaten by people.

Does the LPS33HW contaminate water?

Or is there another way?

The amount of water to be measured is 10 to 700 ml.

I look forward to your answer.

1 ACCEPTED SOLUTION

Accepted Solutions

Hi @JLee.26 ,

Although it would be ok to use LPS33HW since it can measure the pressure of a water column up to 2 bar (so the range 10ml and 700ml is ok) and it can stay in water for indefinite time, the device materials (Ecopack1) are not fully bio-compatible (especially the inside gel), so it's better not to leave the sensor to direct exposure to the water flow.

My suggestion would be to add at least a membrane, but in this case it could be more indicated to add a waterproof membrane in the bottom part of the smart tumbler and use for example the LPS25HB device (or the LPS35HW), which has no gel inside.

You can find HERE some guidelines for ST pressure sensors enclosure in a system, for your reference.

-Eleon

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4 REPLIES 4

Hi @JLee.26 ,

Although it would be ok to use LPS33HW since it can measure the pressure of a water column up to 2 bar (so the range 10ml and 700ml is ok) and it can stay in water for indefinite time, the device materials (Ecopack1) are not fully bio-compatible (especially the inside gel), so it's better not to leave the sensor to direct exposure to the water flow.

My suggestion would be to add at least a membrane, but in this case it could be more indicated to add a waterproof membrane in the bottom part of the smart tumbler and use for example the LPS25HB device (or the LPS35HW), which has no gel inside.

You can find HERE some guidelines for ST pressure sensors enclosure in a system, for your reference.

-Eleon

Hi Eleon

Thank you for answering.

I can't apply the LPS33HW...

Because health is a very sensitive issue...

I have a Plan B.

I will review the IR sensor.

There will be 10 IR sensors on the side of the smart tumbler.

Do you have an IR sensor in a small size?

Hi @JLee.26

I fully understand your point.

ST has a broad range of proximity sensor working in the IR field, that might be useful for your purposes.

You could make the bottom part of the tumbler transparent and place ToF sensors inside it.

If well tuned, they could be able to detect also the refraction index discontinuity surface between air and water when the bottle is in steady state.

-Eleon

Hi Eleon

Thank you for answering.

Your answers help me.

I don't know yet. HaHa.., ^^;

I'm still thinking of how to design...