A hand-washing event logger

The most effective way of combating the spread of super bugs in our hospitals is simple low-tech hand washing. The aim of this project is to accurately log date/time and duration of each hand wash event at a sink. The logger has to be battery powered, unobtrusive and safe. I trialed Radio Frequency IDentification (RFID) with a wrist band on the clinician. The band triggered the logger but these devices have limited proximity.

I thought about a water sensor or an Infrared beam to trigger the logger but these devices produce a considerable lag-time. I am now trialing a piezo-electric transducer. The transducer produces a small current which can be filtered and amplified to trigger an Arduino micro controller. So far, I have solved the false-positive triggering and floating earth problems which produce erroneous readings. The proof of concept trial depicted in the following pictures is very encouraging.

The picture below shows the wave shaping prototype connected to the Arduino. The display shows no activity and a previous 8 second flow of water from the faucet.


The picture below shows filtered and shaped pulses coming from the transducer when the faucet is running.

Next I will add a real-time clock and SD card for logging purposes. The ultimate goal is WiFi linking to a central monitor. That shouldn’t be too hard!

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