Dear Cinzia Muriana this is certainly an important technical question, particularly in the current situation of the corona pandemic. Some relevant information can already been found right here on RG. For example, please have a look at the following potentially useful review article:

A Review of Electronic Hand Hygiene Monitoring: Considerations for Hospital Management in Data Collection, Healthcare Worker Supervision, and Patient Perception

Article A Review of Electronic Hand Hygiene Monitoring: Consideratio...

This review is freely available as public full ext on RG and can be downloaded as pdf file.

Also please see this commercially available system:

Hand Hygiene Compliance Monitoring

https://centrak.com/wp-content/uploads/2019/03/CenTrak_Hand-Hygiene-Overview_081920.pdf (see attachment)

https://centrak.com/solutions/handhygiene-compliance/

Good luck with your work and please stay safe and healthy!

you can also use cameras and do activity /motion detection from their video feeds.

thank you for all responses, which are very useful. I'm addresing all suggestions with care.

My Best

My idea will be: Can do a surface scan on hand skin for before the washing and after the washing.

For example, fast detect skin sebum containmination by using infrared spectroscopy， spoting to hand and reflect to the detector, should be able to process result with in few seconds.

Philip Fung , it is a good idea to which I have thouth, as in fact I'm also looking for sanitizer dispenser based on infrared signals that can count each person that wash hands, but my problem is how to capture the infrared signal and send it to a central PC. May be it exists WiFi sanitizer dispenser with infrared sensor for hand washing monitoring, in which each hand washing motion can be sent via WiFi? Thank you!!

Potentially, using bracelets with proximity sensors, could potentially act as a digital punch-card system to track use of soap dispenser, plus the previous concept that Philip Fung and Aparna Sathya Murthy has stated, which is both the use of infrared scanners as well as a wifi perturbation sensor. The data collected by dispensor then provides timestamp on users overall profile, and potentially this can lead to better contact tracing in a facility.

Cinzia Muriana

https://www.philips.com.cn/c-p/ASH3523WH_93/sensor-faucet-spout

Sorry all in Chinese, but, I think you can do modification from this smart washing tap. It employeed approximity sensor and washing time control. What you need to do is, to grab signal from MCU (I think can be easily from the valve coil signal), send it over to blue tooth module (which you can find from ebay or china Taobao). need a little bit programming you will have what you want.

Here some purchasing links: https://www.ebay.com/itm/303986595886?hash=item46c703582e:g:JCwAAOSwPgtgkqfV

https://www.ebay.com/itm/324513015710?_trkparms=ispr%3D1&hash=item4b8e7ba79e:g:G1cAAOSwcnNgwGOl&amdata=enc%3AAQAGAAACkPYe5NmHp%252B2JMhMi7yxGiTJkPrKr5t53CooMSQt2orsSvhAqMt0wg86xg8aAkgjQJGpLRk9ORLXdVY3ZYHOHd7jeJ5DXDL0IxXuPI8p7xX%252BhkUCb1GbKnUxye3b2j8waT0huX2DMcggOT%252FsNel%252F7RMqUnJIgSVDtQir5ivYSCgLC0r4qbiuJUDQ40p1l25klkfMbf6AQuq2KYiGgaUM%252Bi9HB6EvjJegugFqLBWMQQxJqsPWNHcq9OeOvMm4TReobVYR4d3QhwmvqL0x%252BnHHTLbjlBVpYT73fURKIb9yso3BadWo2Ur%252F1mCI8Y6Cwb0cZruQMEf0L%252Fdvf%252B5JZDV0v8jUPyoZaTN4JknwB4XZneflDKU2zN7jdg%252B%252BQ88KdccJgCpaBLKyR0RpAaLprG3i5k4x0bYzMCSPHbTp2GPKx3%252BR%252FA3CxuUo7eIzfnD1Y4z9KSCCnVRQV4Fgx4A4UL%252FbRw58nrSL%252FlDeYOxWiSwrQqAZ%252BKk%252BCQg04FmWJRZ8jcFbL9oFttCAPoPfeNDB8jIdZbBrrL2kihi%252FCehUDWkSwTpfsLjw2RI5E5oF8b7Gh72pUFI5Yic5n92u1lrEuSoDuo862%252Bt8wO9pAr7jtmma%252FwumeWl791eSlvldKlNFrkWBE7MV2VFNhHFQ4UC05zMeuXxByq8tjg4TeV0BsT0poDhvOi3CjnxYwxP4A8FuifAXZil3DGkccDmQ45wPqgT%252Ff%252FohVvNQXpTj8nKMaZ0sXorntMCQLPzUL63R4ZEmfn1h8Y9IKYs3SnJIxJpaIb7XR1bESLE94zASDmx2DjnVMmpjcOejUrqYsuoKanCLYf0cIawPC%252BDa8tlyFKFE396eE7oh0ex5I%252BrA14LqaPgJ5tCgw%7Campid%3APL_CLK%7Cclp%3A2334524

Philip Fung , thank you again for your suggestion. I'm take a look at the link.

Cinzia