Ph metre

WHY  do you want non contact and will inaccurate reading be acceptable 

I need a non-contact pH meter. Yes, up to 5% to 10% is acceptable

Can you give some details? how to do it link video source etc.

My short answer, as a chemical engineer is, non-contact pH is not possible.  pH is a measure of hydrogen in water (or lack of hydrogen, excess oh- ), so I would say on first thought, you must immerse something into the water.

But now, thinking, thinking, you could immerse something, pull it out and use a camera to assess the pH result.

Are you planning something like this?

www.presens.de/.../sensors

Why is the word 'metre' used as the heading in this article? It should be 'meter'!  'Metre' is a unit of length, similar to a yard.  A 'Meter' is an instrument used to measure a quantity, as in 'thermometer' (measures temperature), 'voltmeter' (measures volts, surprise surprise) and 'speedometer'. It's bad enough seeing these words incorrectly used in low-quality newspapers, but to see it being done within a much-respected scientific discussion group is just too much...

Happy New Year everybody!

P.S. 'Year' is a unit of time, sometimes pronounced 'Yer', as in 'Woss yer name?'

And here in the US... meter is also how we spell the unit of length.   It's just our rebellious nature.  
I've gotten the colour/color thing down, but I still haven't figured out the grey/gray thing.  And I've jokingly said aluminum wrong for so many years that I can't say it right to save my soul.  Or it that sole...

Yes, it is something like this, but it is more professional and simple and useful because my sample is cake cream. The measurement needs to be more practical and easy, and at the same time, it should be a clear measurement, just like a digital pH meter.

1. I want to clean pH probes with a simple method, but I could not find a simple and effective method. I can only do this with ultrasonic cleaners. I don't know what liquid to use for this.

kmikemoo said:

And I've jokingly said aluminum wrong for so many years that I can't say it right to save my soul.

 kmikemoo  I recall lexicographer Susie Dent discussing this one on several occasions.

At one time British English also used 'aluminum' in order to match the ending of the likes of 'platinum' but then later on changed it to 'aluminium' to match the endings of  the likes of 'magnesium' and 'potassium'.

kmikemoo said:

I've gotten the colour/color thing down

Similar sort of story there with both forms being in common use up until around the time Samuel Johnson attempted to standardise spelling. Then Noah Webster came along and attempted to simplify spelling by removing superfluous letters...