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WASHING HAND DETECTOR
2018

Technology probes are a new type of probe that combines the social science goal of collecting information about the use and users of technology in a real-world setting, the engineering goal of field-testing the technology, and the design goal of inspiring users and designers to think of new kinds of technology to support their needs and desires. The washing hand detector project aims to investigate and learn the data-driven design research method known as technology probes through practice. A washing hand detector was designed and installed in a public toilet to study the probability of people washing their hands.
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CONTEXT
 

Washing hands properly removes dirt, viruses and bacteria to stop them spreading to other people and objects, which can spread illnesses such as food poisoning, flu or diarrhoea.

“Hands are easily contaminated with faecal bacteria [poo] when going to the toilet and this can be easily spread on to other things you touch, including food. Unfortunately, not all people consistently wash their hands after going to the toilet or before handling food.”
- Professor Jeremy Hawker, a consultant epidemiologist at Public Health England.

Washing your hands properly should take about as long as singing "Happy Birthday" twice (around 20 seconds).

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Washing hands instruction by NHS

AIM OF THE PROJECT
 

The aim of the project is to study whether people in the Evolution House at Edinburgh College of Art, University of Edinburgh, wash their hands after using the toilet, to investigate the duration of their handwashing, and to evaluate the effects of individual practices on the cleanliness of the environment.

WHY TECHNOLOGY PROBE?

A technology probe is chosen for this study because it is confidential, as the question cannot be researched using observation. It is appropriate, as it records data from simple uses, and it is efficient, as the data needs to be tracked at all times.

TESTING DIFFERENT SENSORS
 

To collect data on whether people are washing their hands, it is necessary to detect if the tap is open. Three different kinds of sensors were tested: the ultrasonic sensor, to detect the distance between water and the sensor; the accelerometer, to detect the vibration of the tap; and the noise sensor, to detect the noise of the water. To determine if people entered the toilet, a digital compass was tested on the door to detect whether the door was open. However, none of these sensors worked properly.

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Testing different sensor and data collected

THE FINAL SENSOR CHOICE
 

Finally, a door switch sensor was attached to the toilet flush handle, to detect if people used the toilet (upper right image). Conducting wires  connected water from the tap to the analog pin of the Arduino (microcontroller), to read the currency in the circuit in order to detect if the tap was open (lower right image) .

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The final circuit

MAKING


To deploy the probe in the toilet, several constituent parts are designed. A bracket was designed to fix the conduct wires on the tap and a clip was designed to fix the door switch sensor on the flush handle. Shells are designed to contain the Arduinos and the power banks. All designed constituent parts are 3d printed. A customised shield integrated all electrical components is built to stack on the Arduino. The probe was pre-tested before the final deployment.

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Design and making processes

DEPLOYMENT

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Video of deloying technology probe

COLLECTED DATA


The two Arduinos recorded at what time the people washed their hands and used the toilets. The Arduino switched on within seconds in the CSV file (image below). The data was analysed and transferred  to real time by Python—a programming language. Plots were created (left image), showing the time people spent washing their hands and using the toilet. The plots show that there are different reasons for the extreme data.

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Data in CSV file

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DATA CLEANING AND ANALYSIS


As the plots on the left, the extreme and hard-explained data are cleaned. Based on the data, users’ behaviours in the toilet are estimated and indicated on the plots.

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REFLECTIONS


ABOUT WASHING HAND


In the washroom where the technology probe was installed, 72% (31 out of 43) of people washed their hands after flushing the toilet. The average time people spent washing their hands was 6.85 seconds, which is much less than the 20 seconds suggested by the NHS. People on the first floor of the Evolution House at Edinburgh College of Art, University of Edinburgh may need to promote hand-washing awareness.

ABOUT THE LIMITATIONS

 

In this project, the technology probe showed low accuracy results. Some data captured was difficult to explain. The assumptions were difficult to confirm, as requesting information on people’s toilet habits is not appropriate. The technology probe as a design research method needs to be combined with other human-centred methods to be more effective in certain situations. If the technology probe could be installed in the toilets on other floors, the data would be more representative. Additionally, the lights on the box may be a distraction to those using the toilet, even if they are only meant to show that the sensors are working properly.

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