Detergents sensorics

Ruzicka, et al. (11) increased the oil solubility gf phosphate ester anions to increase the sensitivity of the Ca electrode. Gavach, et al. (12) and Birch, et al. (13) made detergent sensors for cations and anions. 

R. Gruden, O. Kanoun, and U. Troltzsch, Influence of surface effects on the characteristic curves of detergent sensors, in 9th International Multi-Conference on Signals, Sensors and Devices, 20.-23. Mdrz 2012, Chemnitz, 2012. 

Vivancos JL, Racz Z, Cole M, Gardner JW (2012) Surface acoustic wave based analytical system for the detection of liquid detergents. Sensor Actuator B 171 469-477... 

Enzymes are important catalysts in biological organisms and are of increasing use in detergents and sensors. It is of interest to understand not only their adsorption characteristics but also their catalytic activity on the surface. The interplay between adsorption and deactivation has been clearly illustrated [119] as has the ability of a protein to cleave a surface-bound substrate [120]. 

Cg pH-sensitive film had a dynamic range from 6 to 8 and Cg-film responded at higher pH values (8-10).The membranes showed good reproducibility, reversibility and a short response time (<10 s). They also can be used for at least 3 months without any considerable absolution deviations. These sensors can be used for direct determination of pH in drinking water detergent and dishwasher liquid that have good agreement with pH meter data. 

Introduction of chemical sensors for water quality monitoring. This includes parameters like turbidity, color, surface tension, detergent concentrations, pH-value etc. Optoelectronic systems are used to monitor the turbidity of washing water, which then determines the number of rinsing cycles (aqua-sensor system). 

It is also interesting to look into the future use of sensors in household appliances. An attempt to do this is made in Chapter 6 where the influence factors in this broad field are analyzed. These include socio-economic data of the end users (like age of the population) and their preferences (like savings of energy, water and detergents), ease of use and cost of ownership, as described in Chapter 6.1. One specific and interesting future development can be foreseen - the integration of home appliances into heretofore strictly separated areas, such as... 

It is known from laboratory tests that surface tension measurement can provide reliable information regarding existing detergent concentration. Work is being carried out in various institutes on such sensors for the commercial sector. However, for use in domestic washing machines, only sensors that are extremely inexpensive, maintenance-free and durable are suitable. How much of a breakthrough can be achieved here in the future remains to be seen. 

Another way to achieve high detergency performance while keeping environmental impacts low is by making intelligent products with built-in sensor functions. In these applications, the products can respond to external stimuli and fulfil their task. The inherent sensoric principles of two recent innovations, detergent tablets and dishwashing tablets with built-in rinse aid, will be discussed. 

It becomes clear that research and development in the household and detergency area depend on a profound knowledge of physico-chemical parameters. Thus, an overview will be given of selected physico-chemical methods used in detergency research, most of them based on sensor technologies. 

Fig. 4.7 Typical behavior of a solid detergent product during the first 20 minutes in a commercially available washing machine. Relevant parameters (pH value, conductivity A, surface tension y, peroxide content ) were detected by on-line sensorics.

Conductivity sensors are most commonly used for safety purposes in household appliances. Presence and absence of washing liquor, detergency, and water softener can be easily measured and proper operation ensured [71]. The various applications mainly differ by their design of electrode geometry and methods for electrical measurement. Due to the close relation between ionic conductivity and water hardness, the automatic water softener in an automatic dishwasher can be controlled by a conductivity sensor [72]. To isolate the transmission of the measured value from the process controller, the conductivity sensor could incorporate an opto-electronical coupling [73]. Thus, protective insulation of the electrodes in a washer-dryer could be ensured. 

Detergent Products with Built in Sensor Functions 1109... 

In some other washing machines that have recently entered the market, the wash load is detected by a weight sensor that measures the elongation of the spiral springs where the tub is suspended inside the washing machine. This is known as a load size indicator . Based on information from the detergent manufacturer, it tells the customer how much detergent to use. 

In automatic dishwashers, amount of dirt on crockery and cutlery can be measured with a radar sensor [87] or with a device that uses the reflectivity of an integrated surface [88]. Thus, the load of the washing liquor with soil and detergency can be measured. 

The basis for this latest development was a displacement sensor designed by Micro-Epsilon. The sensor combines unbalance detection and measuring of the load in a single sensor module. With the information provided by the sensor, the electronic controller of the machine detects the laundry load and suggests to the user the required amount of detergent Moreover the necessary amount of water is controlled. By sensing the unbalance of the drum, the number of revolutions... 

Chemical sensors for water quality determination. The parameters measured include turbidity, color, surface tension, detergent concentration, pH-value etc. 

The technical development of all types of washing machines and their sensor and control systems depends to a large extent on the use of appropriate detergents, their chemical composition and physical qualities. 

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