Arduino - Secure Your Belongings: Detect Theft and Send Email Alerts

In this guide, we'll show you how to protect your items using an Arduino and a force sensor. The steps include how to set up a system that tells you by email if someone tries to take your belongings. We'll explain how to set up the Arduino, connect the force sensor, and program it to send email alerts through Gmail. You'll learn how to do everything step by step and see how it can be helpful in real situations.

Arduino Theft detection Email Notification

Hardware Required

1×Arduino UNO R4 WiFi
1×USB Cable Type-C
1×Force Sensor
1×10 kΩ resistor
1×Jumper Wires
1×(Optional) DC Power Jack
1×(Recommended) Screw Terminal Block Shield for Arduino Uno
1×(Optional) Transparent Acrylic Enclosure For Arduino Uno

Or you can buy the following sensor kits:

1×DIYables Sensor Kit (30 sensors/displays)
1×DIYables Sensor Kit (18 sensors/displays)
Please note: These are Amazon affiliate links. If you buy the components through these links, We will get a commission at no extra cost to you. We appreciate it.

About Force Sensor and Gmail

We offer detailed tutorials on Force Sensors and Gmail. Each guide provides thorough details and instructions step by step on hardware setup, how it works, and how to connect wires to Arduino, including coding for Arduino. For more information, visit these links:

How the theft detection system work

The force sensor checks the weight of an item when you place it on the sensor. When you put your item on it, the Arduino records its weight. If the item is removed, the weight changes. The Arduino notices this change and emails you to tell you that your item has been moved.

Wiring Diagram between Force Sensor and Arduino

Arduino Force Sensor Wiring Diagram

This image is created using Fritzing. Click to enlarge image

Arduino Code

/* * Created by * * This example code is in the public domain * * Tutorial page: */ #include <WiFiS3.h> #include <ESP_Mail_Client.h> #define WIFI_SSID "YOUR_WIFI_SSID" // CHANGE IT #define WIFI_PASSWORD "YOUR_WIFI_PASSWORD" // CHANGE IT // the sender email credentials #define SENDER_EMAIL "" // CHANGE IT #define SENDER_PASSWORD "xxxx xxxx xxxx xxxx" // CHANGE IT to your Google App password #define RECIPIENT_EMAIL "" // CHANGE IT #define SMTP_HOST "" #define SMTP_PORT 587 #define FORCE_SENSOR_PIN A0 // Arduino pin connected to the FSR and 10K pulldown #define THRESHOLD 100 // may need to callibrate this value SMTPSession smtp; void setup() { Serial.begin(9600); WiFi.begin(WIFI_SSID, WIFI_PASSWORD); Serial.print("Connecting to Wi-Fi"); while (WiFi.status() != WL_CONNECTED) { Serial.print("."); delay(300); } Serial.println(); Serial.print("Connected with IP: "); Serial.println(WiFi.localIP()); Serial.println(); pinMode(DOOR_SENSOR_PIN, INPUT_PULLUP); // set Arduino pin to input pull-up mode door_state = digitalRead(DOOR_SENSOR_PIN); // read state } void loop() { int forceValue = analogRead(FORCE_SENSOR_PIN); if (forceValue < THRESHOLD) { Serial.println("Alert! Someone has stolen your stuff!"); String subject = "Email Notification from Arduino"; String textMsg = "This is an email sent from Arduino.\n"; textMsg += "Alert! Someone has stolen your stuff!"; gmail_send(subject, textMsg); } } void gmail_send(String subject, String textMsg) { // set the network reconnection option MailClient.networkReconnect(true); smtp.debug(1); smtp.callback(smtpCallback); Session_Config config; // set the session config config.server.host_name = SMTP_HOST; config.server.port = SMTP_PORT; = SENDER_EMAIL; config.login.password = SENDER_PASSWORD; config.login.user_domain = F(""); config.time.ntp_server = F(","); config.time.gmt_offset = 3; config.time.day_light_offset = 0; // declare the message class SMTP_Message message; // set the message headers = F("Arduino"); = SENDER_EMAIL; message.subject = subject; message.addRecipient(F("To Whom It May Concern"), RECIPIENT_EMAIL); message.text.content = textMsg; message.text.transfer_encoding = "base64"; message.text.charSet = F("utf-8"); message.priority = esp_mail_smtp_priority::esp_mail_smtp_priority_low; // set the custom message header message.addHeader(F("Message-ID: <>")); // connect to the server if (!smtp.connect(&config)) { Serial.println("Connection error: "); Serial.print("- Status Code: "); Serial.println(smtp.statusCode()); Serial.print("- Error Code: "); Serial.println(smtp.errorCode()); Serial.print("- Reason: "); Serial.println(smtp.errorReason().c_str()); return; } if (!smtp.isLoggedIn()) { Serial.println("Not yet logged in."); } else { if (smtp.isAuthenticated()) Serial.println("Successfully logged in."); else Serial.println("Connected with no Auth."); } // start sending Email and close the session if (!MailClient.sendMail(&smtp, &message)) { Serial.println("Connection error: "); Serial.print("- Status Code: "); Serial.println(smtp.statusCode()); Serial.print("- Error Code: "); Serial.println(smtp.errorCode()); Serial.print("- Reason: "); Serial.println(smtp.errorReason().c_str()); } } // callback function to get the Email sending status void smtpCallback(SMTP_Status status) { // print the current status Serial.println(; // print the sending result if (status.success()) { for (size_t i = 0; i < smtp.sendingResult.size(); i++) { // get the result item SMTP_Result result = smtp.sendingResult.getItem(i); Serial.print("Status: "); if (result.completed) Serial.println("success"); else Serial.println("failed"); Serial.print("Recipient: "); Serial.println(result.recipients.c_str()); Serial.print("Subject: "); Serial.println(result.subject.c_str()); } Serial.println("----------------\n"); // free the memory smtp.sendingResult.clear(); } }

Quick Steps

  • If this is the first time you use Arduino Uno R4, see how to setup environment for Arduino Uno R4 on Arduino IDE.
  • Connect the Arduino board to the force sensor.
  • Place your items on the force sensor.
  • Connect the Arduino board to your computer using a USB cable.
  • Launch the Arduino IDE on your computer.
  • Select the right Arduino board (Arduino Uno R4 WiFi) and COM port.
  • Open the Library Manager by clicking the Library Manager icon on the left side of the Arduino IDE.
  • Look for ESP Mail Client and select the one made by Mobizt.
  • Press the Install button to add the ESP Mail Client library.
Arduino ESP Mail Client library
  • Copy the code and open it with the Arduino IDE.
  • Update your WiFi details (name and password) in the code by editing WIFI_SSID and WIFI_PASSWORD.
  • Update the sender's email and password in the code by editing SENDER_EMAIL and SENDER_PASSWORD.
  • Change the recipient's email in the code by editing RECIPIENT_EMAIL. The recipient's email can be the same as the sender's email.


  • The sender's email address must be a Gmail account.
  • The sender's password should be the App password you obtained in the previous step.
  • The recipient's email address can be from any email provider.
  • Click the Upload button in the Arduino IDE to send code to the Arduino.
  • Open the Serial Monitor.
  • Remove items from the force sensor.
  • Look at the results on the Serial Monitor.
Alert! Someone has stolen your stuff! #### Email sent successfully > C: Email sent successfully ---------------- Message sent success: 1 Message sent failed: 0 ---------------- Message No: 1 Status: success Date/Time: May 27, 2024 04:42:50 Recipient: Subject: Email Notification from Arduino ----------------
Autoscroll Show timestamp
Clear output
9600 baud  
  • Look in your recipient's email inbox. You will receive an email like this:
Arduino theft detection email

Video Tutorial

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