How Do Automatic Door Sensors Work

Automatic door sensors are energy-efficient, and make things convenient. Plus, some of these sensors add a sense of security. While some door sensors automatically open doors for you, others alert you when the connected door or window opens.

But how do these automatic door sensors work? If you have been wondering about it, you have come to the right place.

In this post, we will explore how automatic door sensors work. And at the end of the post, you will find some of the best door sensors that you can pick for your home.

Let’s get going, shall we?

How Do Automatic Door Sensors Work

As noted earlier, there are quite a few varieties of door sensors and their working may vary on the type and their application. For instance, the door sensor used in your local McDonald store is different than the ones used in your house. The same can be said about the door sensors used.

Types of Sensors

There are four primary types of door sensors.

  • Optical sensors or motion sensors
  • Infrared sensors
  • Pressure sensors
  • Circuit-based or contact sensors

1. Optical Sensors or Motion Detectors: Optical-based sensors are the most popular ones used for commercial sliding doors. These sensors are generally placed on top of doors or at the corners of doors, with the antenna facing towards the entrance.

The antenna sends out microwave signals to detect motions. Once it detects a motion, it signals the doors to slide open or unlock. Simple, right?

The only issue with it is that it is a single sensor. It doesn’t have any additional sensors to measure the change in ambient temperature or vibrations. So if a person were to stand completely still, the sensor would not trigger the automatic doors to slide open.

2. Infrared sensors: Infrared sensors have one advantage over optical door sensors. They are triggered even when a person is standing still in front of the door. These sensors detect the change in thermal energy across their line of vision.

If a person walks across its line of vision, the sensor will detect the change in temperature due to the body heat and signal the door to slide open.

These sensors, referred to as Passive Infrared (PIR) sensors, are customizable to some extent. For example, you can program them to ignore small changes in temperature. Like if your pet tries to walk out of the front door, it won’t open. The compact form factor makes them easily usable inside homes.

3. Pressure sensors: Pressure-based sensors are now almost archaic. These sensors use a pressure mat in front of the door. If the mat detects a certain amount of pressure, it will signal the door to open. It gives you some amount of customization. For example, you can set the amount of pressure.

It’s not without limitations. For instance, a door equipped with a pressure sensor will stay open if a person stands on the mat for an extended time.

4. Circuit-based sensor or Contact sensor: Contact sensors are unlike the ones above. These sensors alert you when you open the door and alert the homeowner when it detects a breach. That’s the reason circuit-based sensors are typically the best sensors for homes and garages.

Ring Alarm Contact Sensor

They are small and can easily be attached on top of your front door or your patio door. And the good news is that some of these door sensors are smart and can integrate with other smart products like a security camera or a smart light.

Contact-based door sensors usually come in two parts. The larger part (that sticks to the door casing) comes with a Reed sensor, whereas the small part (that sticks to the door frame) bundles a small magnet. When the door stays closed, the circuit is completed.

So when you push the door open, the circuit is broken and the sensor alerts the hub or receiver to sound the alarm and send notifications.

These sensors are compact and small and easily fit into most door frames. The small form factor means that this device can be placed anywhere – a window or a door.

Again, contact sensors are available in many different types. And contact sensors make the best door sensors for homes and garages. Now that’s settled, let’s see some of the best contact-based door sensors,

4 Best Contact-based Door Sensors

1. Bistee Store Wireless Door Alarm

Bistee Store’s wireless door alarm is affordable and simple. It comes with a contact sensor and a receiver. Whenever the sensor trips, it signals the receiver and it alerts you with a chime. The highlight of this door sensor is the plethora of alarm tones and you get to choose from 58 melodies. Plus, you can also bump their volume as per your preference.


The receiver has decent range. The best part is that you can place 2 receivers around your house if you do not want to miss the alerts. The receiver has a blue light indicator, and at times, it can be a little distracting.

The battery life isn’t bad either, and a single 12V 23A battery lasts half a year. Note that the battery life depends on the frequency of usage.

It works as advertised, and it’s a pretty good deal. And if you are looking to save money, it’s a good pick. However, there’s one area where you might have to settle is the durability.

2. YoLink Door Sensor

One of the advantages that the YoLink dor sensor has over the one above is the Alexa integration. This means an Alexa speaker can alert you when the door opens. It uses LoRa (Low Range Radio) technology to make the door sensor apt for large houses.  


The YoLink door sensor bundles a small hub for the smart home integration to function. The good thing is that you can pair other smart devices like a security camera later on.

It delivers a good performance and is quick to react. It’s a popular door sensor and has several positive reviews on Amazon.

3. Wyze Home Entry Sensor

Up next, we have Wyze’s Entry sensor for both doors and windows. It is every bit a modern device and comes with Amazon Alexa compatibility. You can add the company’s security camera to the setup (it needs Security System Core Kit to function) and set it to record every time the door sensor trips.


The battery life is not bad either. On moderate use, it can last up to 18 months. Like most door sensors, this one also alerts you via phone notifications when the sensor is tripped.

4.  Ring Alarm Contact Sensor (2nd Gen)

If you are already on the Ring smart home ecosystem, the Ring Alarm contact sensor will be your best bet. It’s small and compact, and the wider maximum gap ensures that it fits most doors and windows with ease


It’s super simple to install, and several users have pointed this out in their reviews. It comes with 3M adhesive tapes. Alternatively, you can use the in-box screws if you’re looking for permanent installation.

It needs a hub (Ring Alarm Base Station) to function. The good news is that the hub has a pretty good range and alerts you even when the sensor is at a distance.

Open Sesame!

Door sensors make things convenient, whether they’re the automatic door sliders or the simple contact sensors. If you are looking to up the security of your home, the latter makes for good addition as key entry points in your house. On the other hand, if you have sliding French doors, you can check out something like the Request to Exit PIR Motion Sensor to unlock the door automatically.

Last updated on 06 June, 2022

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