I am designing a product for medical liquid sensing and I am a bit lost in all your products.
My tank is about 20cm high, and I need a 1mm accuracy (so 200 divisions). My sensor PCB can be up to 3cm wide (so 20cm x 3cm for sensor).
The distance between the liquid and the PCB is 2.5mm PVC, 0.5-1mm air, and 1.5mm ABS.
I was wondering if you had recommendation on which product to use, and how many (segmentation of the sensors). I already have a microprocessor in my product and only need the sensing part (via like I2C).
Can you please provide additional details before we suggest a sensing method?
1. Is the liquid being sensed conductive or non-conductive? Is there any possibility of the liquid being grounded? (Note that the sensing method is dependent on the type of liquid).
2. If the liquid is conductive and grounded, can it be ensured that it is always connected to the ground and its not an accidental ground connection? If its not grounded, can it be ensured that there is no possibility of accidental grounding?
3. What is the dimension of the inner part of the container where the liquid will be present? And what is the volume of the container?
4. Is the air gap provided for thermal isolation? Can this be avoided for improvements in liquid level sensing?
The liquid a composition of different body fluid that can vary in conductivity from 1 to 50 mS. It is not grounded and there is a drip chamber so accidental grounding should not happen and the device is battery operated.
The dimension of the inner part of the container is about 5cm x 15cm x 18cm, but we plan wider container with the middle dimension being bigger. The volume will be from 1.2l to 2.5l with the 5cm (depth) and 18cm (height) not varying. So there is about 5cm of liquid in front of the sensor.
The air gap is variable play gap, the container is a single use consumable and it is mounted on another part containing the sensor, when mounted, there is a small possible air gap as the flatness of the consumable container is not 100% guaranteed because of production constraints.
Obtaining an accuracy of 1 mm would not be possible with the current configuration. The main issue is the variable air gap formed between the disposable container and the main container. Would it be possible to mechanically change the design to avoid this?
If it is not possible, can the accuracy be close to 5 mm?
Can you tell me what you would recommend if I can get rid of the air gap, and what you recommend if I cannot (with 5mm accuracy)? I will then experiment with it and see what I get.
In both cases, I would recommend our PSoC 4S line of devices - PSoC 4000S, PSoC 4100S and PSoC 4100S plus.
You can evaluate the performance using the kits:
CY8CKIT145-40XX - PSoC 4000S
CY8CKIT-041-41XX - PSoC 4100S
CY8CKIT-149 - PSoC 4100 S Plus
PSoC 4100S Plus is the most advanced CapSense IP with a higher GPIO count as well.