Physical principles

The following are the features of the device and alternative options for each feature:

Temperature sensing
Alternative 1: Infrared camera: Takes body temperatures of people who pass by through thermal imaging.

Alternative 2: Digital thermometer: Uses infrared technology to measure the temperature of the body. It is handheld and operated by pressing a button.

Alternative 3: Contactless infrared forehead thermometer: Uses infrared scanner and infrared ranging sensor to take the temperature. The sensor senses when someone is near the device and then the scanner will measure the temperature of the temporal artery in the forehead. It is completely hands-free.


QR scanning
Alternative 1: Arduino QR scanner: Small device with CMOS scanner and QR code decoder which can be embedded easily in different mechanical equipment.

Alternative 2: Mobile device application: The phone camera captures the image of the QR code and the software decodes it, then translates the information.


Temperature display
Alternative 1: LCD screen: Liquid-crystal display screen which can display images in colour or monochrome. 


Alternative 2: Segment screen: Displays numerals in monochrome.


User interface
Alternative 1: ON/OFF, red/green, display number of people in the store.

Light control
Alternative 1: LED lights: Red and green light-emitting diodes which light up when sufficient voltage is supplied.


Communication with database
Alternative 1: Direct upload (constant internet connection): Data collected is automatically uploaded to the central database immediately after someone scans a QR code. This requires constant internet connection of the device.

Alternative 2: Uploaded manually each day: Store owners will have to upload the data collected in the device at the end of each day to the central database manually.

Alternative 3: Direct upload (when there is internet connection): Data collected is automatically uploaded to the central database once the device is connected to the internet. 

Mechanical (enclosement, support, safety, mobility, etc.)
Alternative 1: Fixed: Device is fixed to the ground and cannot be moved.


Alternative 2: Portable: Device is mounted on a stand or on the wall and can be easily moved around.


Alternative 3: Handheld: Device is held in the hand of the operator.

Privacy (input)
Alternative 1: Phone number + name (optional): People will provide their phone numbers when registering for a QR code and have a choice of whether or not to put their names. This way people without phone numbers can choose to register with a family member’s number instead.

Alternative 2: Only phone number: People provide their phone numbers when registering for a QR code.

Alternative 3: Unique user identifier number: Each person is given a unique identification number which can be used to trace their personal information.

Energy supply
Alternative 1: AC power supply: Device runs on AC power and has to be plugged into sockets to operate.

Alternative 2: Solar power: Environmentally friendly source which draws its power from solar energy.

Alternative 3: DC rechargeable batteries: Device runs on batteries which can be recharged before use.

Threatened user information (infected)
Alternative 1: Contact tracing centres disclose only place, date and time of possible interaction with infected individual.