Ph sensors: for guaranteed sophisticated ph measurements

Ph sensors are indispensable in many areas. But those who think that this is only something for laboratory chemists and physicians are mistaken. In everyday life, too, there are now many reasons to use the ph value to be determined precisely – in the meantime this can even be done fully automatically.

Ph sensors are found in many areas of life

Most people do not think about the ph value – until they a reason HAVE. However, the question then often arises as to which sensors are to be used and how the most precise measurements possible are to be carried out. The determination of the ph value does not necessarily require electronic sensors, but is also possible with test strips, for example.

Theoretically, one could even call the human tongue a sensor for determining ph values, because whether something tastes sour or sweet is strongly related to this value. lemons taste more sour than, say, a sweet prune juice. And also in the kitchen we are constantly confronted with the ph value without noticing it. Baking powder for example, is a product based on the action of acids and bases. The difference between acidic and basic solutions however, most people are not even aware of this.

Simplified, it can be reduced to the fact that an acidic solution contains a high concentration of hydrogen ions has an alkaline solution corresponding to a low concentration shows. To assess whether the value is high or low, the hydrogen ion concentration of pure water serves as a reference. This concentration in a solution is usually referred to as ph value.

The ph scale

So the scale that sensors or test strips use always refers to the standardized ph value, according to which they must be calibrated to display correct results. Modern gauges must be determined by calibration systems can be adjusted, on many models these are already integrated internally, on others an external calibration is foreseen. This is especially true for professional applications. The following ph-values correspond to different solutions one has to deal with in everyday life.

this ph value scale shows how the ph value measured by ph sensors is to be interpreted.
(graphic: shutterstock – alhovik, #3)

Ph-value from acid to base:

  • 1 – gastric acid
  • 2 – lemon juice
  • 3 – orange juice
  • 4 – tomato juice
  • 5 – black coffee
  • 6 – human urine
  • 7 – distilled water
  • 8 – salt water
  • 9 – baking powder
  • 10 – milk of magnesia
  • 11 – ammonia solution
  • 12 – soapy water
  • 13 – bleach

For biology, and therefore also for medicine, the ph value and reliable sensors for its precise determination play an important role. So a shift of ph-value in blood or urine on certain diseases such as z. B. diabetes indicate. While a test strip can be used for the initial determination, a ph measuring device in the laboratory is necessary for the exact determination, which also creates further analyses for the attending physician.

Not only physicians and chemists need reliable ph sensors

Everywhere test strips not sufficient for the precise determination of the ph value, ion selective sensors are used in corresponding measuring devices for various applications. Very common is the so-called galvanometry, in which a glass surface coated with potassium chloride solution filled sphere with a glass membrane is immersed in the respective measuring liquid.

The hydrogen ions tend to be based on the glass surface to accumulate and thus create galvanic voltage within the sphere, different from an independent reference electrode. the difference can be used to determine the ph value, which is then usually shown on a digital display. Another measuring method uses ion-selective field-effect transistors. Here, too, a membrane is used, on whose surface hydrogen ions accumulate and the current permeability of the membrane connected transistor influence. Measured values can also be derived from this. But for which applications in everyday life are ph sensors actually necessary?? the answer surprises many laymen and shows that there is a great need for precise measuring instruments.

Typical applications for the use of ph sensors:

  • Aquaristicsto determine the right environmental conditions for certain fish species
  • agriculturefor the determination of the ph-value of soils and products such as fruit, wine, etc.
  • Swimming pools and domestic poolshere the ph value is an indicator of the quality of the water.
  • Medicineespecially the analysis of blood and urine)
  • Cosmeticsz. B. For the production of ph-neutral washing substances and other products
  • drinking watermonitoring the quality of drinking water

In addition, there are many other areas such as the food chemistry, where ph values always play a big role. in short: even private individuals sometimes need accurate sensors for ph determination, for example if they run an aquarium or have their own swimming pool. But also in building construction, when using mortar or other substances, the ph value of the floor may be important to prevent corrosion and other problems.

As an alternative to pH sensors, it is also possible to determine pH levels chemically. Test strips and, as visible here, test tablets and test tubes help. (Photo: shutterstock - oneSHUTTER oneMEMORY, #1)

As an alternative to ph-sensors, it is also possible to determine the ph-value by chemical means. Test strips and, as visible here, test tablets and test tubes help. (photo: shutterstock – oneshutter onememory, #1)

Automatic measurement of the water in the home pool

Whether you have a fully developed swimming pool or only a somewhat larger pool, it doesn’t matter. If you want your children and yourself to have fun in the water, you should measure the ph value of the water regularly and monitoring. The consequences of a shift in the ph value in the pool are sometimes serious and can be serious in the event of a prolonged absence (e.g. B. On vacation) to real damage lead.

ph value too low: risk of corrosion damage!

When the ph is too low, the water acts as a mild acid that can cause corrosion damage. Fittings, the mortar of the tiles or even the functioning of pumps, cleaning and filtering systems can be affected. For cleaning purposes, many owners like to add a little more chlorine to the water – this also influences the pH value and, in case of doubt, can lead to irritation of the skin and allergic reactions. Too little chlorine, on the other hand, can promote an environment in which increased bacteria and algae thrive, which is something you usually want to avoid in the pool.

checking the ph value daily with a test strip is sufficient in principle, but it always involves a lot of effort – and is not always possible, especially when you are away. Modern sensors can remedy this situation and report their analytics data to an app or other services via an automatic function, so that the owner is always informed about the current pH value and can intervene if necessary.

Ph sensors have long been digital. As seen here, they perform tasks in agriculture and horticulture, are often read by app from the smartphone. in the age of iot, automatic ph measurement delivers data directly to the ERP system. (photo: shutterstock: deyan georgiev)

Also farmers benefit from automatic measuring equipment, they show you immediately when the soil values are no longer right and the crops are in danger. because plants react very sensitively to shifts in the ph value. They also know that hobby gardener with their own greenhouse in the garden.

Another advantage of a meter calibrated via calibration systems is that the values are very reliable and there is no need to purchase test strips and test tablets, which reduces follow-up costs. Especially when there is a constant need for measuring the ph value, the one-time purchase of a precise electronic measuring instruments ultimately saving money.

Accuracy plays an important role depending on the field of application in private or professional environment. For example, if you want to keep very sensitive seawater fish in your aquarium, you have to pay very close attention to the correct ph value. measurement errors and inaccuracies can then not be afforded. Similarly, for laboratory applications in the medicine, the food technology and the agriculture.

Conclusion: good ph sensors need not be expensive today

In the past, high-quality meters were only useful for professionals because the purchase price in no relation to the benefit stood. For most non-professional applications, therefore, the test strip procedure usual. This has changed greatly with the drop in the price of electronic devices. Even high quality instruments from premium manufacturers are nowadays affordable for laymen and interested amateurs.

In particular smartphones and app control has the permanent control of ph-values made possible in all areas. But even inexpensive devices from the far east are easily sufficient for many applications in terms of their precision. However, if you need reliable values that can be used in court under certain circumstances (for example, in agriculture or food quality control), you should always use a calibrated model, whose calibration systems ensuring precise results even with infrequent use.

Photo credits: © shutterstock – cover artstore, #1 oneshutter onememory, #2 deyan georgiev, #3 alhovik

About the author

Marius beilhammer, born in 1969, studied journalism in bamberg, Germany. He has been writing for technical magazines for many years and is also a freelance author on various market and business topics. As a Franconian with a happy nature, he always finds the balance in his work between ease and comprehensive know-how thanks to his pronounced affinity for technology.

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