Building a Touchless Distance Monitor & Handwashing Timer

Parts You'll Need

This project is sourced from another site, not written by us — this list is our best match of their components against what we stock, not a verified bill of materials. Always check the original blog (linked above) for the actual parts list before buying.

Arduino UNO R3 Board (Compatible) – ATmega328P Microcontroller with USB Cable Rs. 999.00
Ultrasonic Sensor Module HC-SR04 Rs. 89.00
ESP32 WiFi+Bluetooth CP2102 Development Board Rs. 520.00
Piezo Buzzer (Big) 6-12V Rs. 45.00
10pcs 5mm RED Diffused Light Emitting Diodes - LEDs Set Rs. 39.00
2-Slot 18650 Holder with Protective Cover and On/Off Switch – Case Rs. 109.00
MB102 Adjustable Breadboard Power Supply Module (3.3V & 5V) for Arduino & Raspberry Pi Rs. 139.00
400 Points Mini Solderless Prototype PCB Breadboard High Quality Rs. 89.00
Jumper Wire 10 Pin Male To Male 20cm Rs. 45.00
Jumper Wire 10 Pin Male To Female 20cm Rs. 45.00

Selected: Rs. 0.00

We don't carry yet: AA / AAA Battery + Holder

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How It Works

The Touchless Distance Monitor & Handwashing Timer operates as an interactive embedded system controlled by an Arduino Uno microcontroller. At its core, the system utilizes an HC-SR04 ultrasonic sensor to calculate proximity by emitting a high-frequency sound wave and measuring the time it takes for the echo to bounce back from a nearby object or user. The Arduino Uno processes this time interval into a distance measurement. When a user approaches within a predefined threshold, the system triggers active feedback components: an LED illuminates and a buzzer sounds to indicate a proximity event or to start a timed handwashing routine. A push-to-on switch is integrated into the circuit to allow manual resetting or mode toggling by the user. Additionally, an HC-05 Bluetooth module enables wireless serial communication, permitting the Arduino to transmit distance metrics and status updates to external Bluetooth-enabled devices like smartphones or computers. The entire circuit is powered reliably using either a 5V battery with a battery holder or an external 5V adaptor, ensuring stable voltage regulation across all connected peripherals.

Why Build This

Design and deploy an undergraduate-level public health technology prototype capable of enforcing automated social distancing alerts.

Implement time-based hygiene protocols by integrating acoustic and visual feedback systems into a single embedded controller.

Establish wireless telemetry links using Bluetooth modules to monitor proximity sensor data remotely on external interfaces.

Real-World Application

Public health safety in crowded places such as markets, malls, and offices to maintain social distancing and encourage proper handwashing habits.

Skills You'll Learn

Ultrasonic distance ranging

serial communication via Bluetooth

digital I/O control

buzzer tone generation

basic power management

Safety Precautions

Ensure proper wiring and power supply ratings to prevent short circuits.

Technology Tags

ARDUINO

ULTRASONIC SENSOR

BLUETOOTH

HC-SR04

HC-05

BUZZER

LED

Frequently Asked Questions

Can I power this project using a standard 9V battery instead of a 5V source?

It is recommended to use the specified 5V battery or 5V adaptor. Powering the logic components and sensors with unregulated higher voltages can damage the Arduino Uno or peripherals.

How does the HC-05 Bluetooth module pair with my smartphone?

The HC-05 acts as a serial bridge. Once wired to the Arduino's digital pins (or software serial pins) and powered, you can search for it in your phone's Bluetooth settings and pair using the default PIN (usually 1234 or 0000).

What should I do if the ultrasonic sensor gives erratic distance readings?

Ensure the HC-05 and HC-04 wiring is secure, verify that your 5V power supply provides sufficient current for both the sensors and the buzzer, and check for obstacles directly in front of the ultrasonic transducer.