FAQ

TUYA Zigbee sensors are essentially IoT devices that communicate using the Zigbee protocol and can connect to the Tuya smart ecosystem. Simply put, they act like the "nerve endings" of a smart home, sensing environmental changes (such as door and window opening/closing, and human movement), then transmitting this information to the "brain" (gateway) via Zigbee signals, ultimately displaying or triggering automated scenarios in the app.

Their core features are low power consumption and stable networking, but they require a Zigbee gateway to function.

Common TUYA Zigbee sensors include:

• Door and Window Sensors: Monitor the opening and closing status of doors and windows, used for security alarms, and linked to lighting and air conditioning.
• Human Movement Sensors: Detect human movement within their range, used to turn lights on when someone enters and off when they leave.
• Temperature and Humidity Sensors: Monitor ambient temperature and humidity in real time, and can be linked to air conditioners and humidifiers to provide data for constant temperature and humidity environments.
• The human presence sensor detects stationary or slightly moving human bodies and is used in scenarios such as studies and bathrooms where lights need to be kept on for extended periods.

Please note that Zigbee samrt home devices cannot connect directly to Wi-Fi; they must be connected to the network and controlled through a Zigbee gateway.

Millimeter-wave radar sleep monitors and fall detectors can remotely and imperceptibly "understand" a person's posture and subtle vital signs, making them particularly suitable for protecting the health and safety of the elderly or family members. The core of these devices is the transmission of millimeter waves in the 60GHz band and the reception of echoes reflected from the human body. It acts like a high-precision "vibration detector," capable of capturing two key types of information even through clothing or thin blankets:

Vital Sign Monitoring: By capturing millimeter-level micro-movements in the chest cavity caused by breathing and heartbeat, it analyzes sleep quality, respiratory rate, and heart rate.

Behavioral Posture Recognition: By analyzing changes in "point cloud" data generated by body movement, it can accurately distinguish between normal walking, sitting, turning over, and sudden falls.

Compared to cameras or smart bracelets, millimeter-wave radar devices have significant advantages:

• Imperceptible and Privacy-Protecting: No need to wear them, and there are no cameras, so there's no feeling of being "monitored."
• 24/7 Operation: Unaffected by light or moisture, it can operate stably in dark bedrooms or damp bathrooms.

When choosing a radar, focus on the following three aspects:

• Frequency Band: Only 60GHz radar can accurately detect millimeter-level movements such as breathing and heartbeat. 24GHz radar has very low resolution (approximately 60cm) and cannot detect chest rise and fall.
• Accuracy: Focus on the product's fall detection accuracy and false alarm rate. A truly effective product should have a fall detection accuracy of over 95% and a false alarm rate below 2%.
• Scene: Choose based on the area you want to monitor (e.g., bed, bathroom, living room): *The effective detection range of a 60GHz radar is typically 1-3 meters, making it more suitable for mounting on the wall or ceiling above the bed, directly facing the bed area.

For monitoring a large living room or hallway, ensure the radar's detection angle covers the entire area.

An active infrared detector is a device that detects targets by emitting and receiving infrared light. You can think of it as an invisible "light wall" or "light net." When a person or object interrupts this light path, it immediately triggers an alarm.

Core working principle: An invisible warning line. It mainly consists of an infrared transmitter and an infrared receiver. Its working principle can be broken down into three steps:

• Emitting a beam: The infrared LED inside the transmitter emits a modulated, invisible infrared beam.
• Forming a warning line: This infrared light beam is directed to the corresponding receiver, forming an invisible warning line between them.
• Triggering the alarm: Under normal circumstances, the receiver can stably receive the light signal. Once an object of sufficient size (such as a person) passes by, blocking or attenuating the beam to a certain extent (e.g., completely blocking it or blocking a given percentage), the signal sensed by the receiver changes, triggering an alarm to the alarm control panel.

To reduce false alarms, these detectors typically use pulse-modulated infrared beams and have a minimum blocking time (e.g., more than 40 milliseconds before alarming), effectively filtering out brief interferences such as flying insects and falling leaves. Modern products also offer dual-beam, triple-beam, and quad-beam configurations, requiring simultaneous blocking of multiple beams to trigger an alarm, further improving reliability.

Active Infrared Detectors vs. Passive Infrared Detectors:

Active Infrared Detectors: These actively emit and receive infrared light. If the light is blocked, they trigger an alarm. Similar to a point-to-point "grating" or "electronic fence," they are commonly used for perimeter security, entrances, and other specific location surveillance.

Passive Infrared Detectors (PIR): These passively receive changes in thermal radiation emitted by objects in the environment (such as humans). They trigger an alarm when the infrared radiation emitted by a moving human differs from the background temperature. They are typically used for human movement detection in indoor spaces (such as room corners).

A passive infrared detector (PIR) is the most common motion sensor in home and office environments. Its core characteristic is its "passive" nature; it doesn't emit any energy itself, but passively "listens" to changes in infrared radiation already present in the environment.

If an active infrared detector is like "actively emitting a beam of light to find its way," then a passive infrared detector is like a "lurking sentinel," quietly sensing subtle changes in the surrounding temperature.

Core Working Principle: A Sentinel Capturing "Temperature Differences" Its working principle can be simply understood as "sensing thermal motion." The core basis is that any object in nature with a temperature above absolute zero (-273°C) emits infrared radiation, and the higher the temperature, the stronger the radiation.

The specific workflow is as follows:

• Core Components:

  The two most critical components inside a PIR sensor are the pyroelectric sensor and the Fresnel lens.

  Pyroelectric Sensor: The core sensitive element, capable of converting changes in infrared radiation into weak electrical signal changes.

  Fresnel Lens: This is a "special magnifying glass" covering the sensor, dividing the surrounding space into dozens of alternating bright and dark "warning zones." When a person moves, they alternately enter the "bright zone" and "dark zone" through the lens, generating a constantly changing infrared radiation signal on the sensor.

• Detection Principle:

  Static Equilibrium: When no one is in the room and it is stationary, the temperature of the walls, furniture, and other objects in the room is stable, and the infrared radiation they emit is constant. The pyroelectric sensor receives a stable background radiation and is in equilibrium, at which point there is no signal output.

  Dynamic Change: When a human body (body temperature approximately 37°C) enters the detection area and moves, the infrared radiation from this person creates a temperature difference of approximately 17°C between the human body and the surrounding environment (such as a wall at 20°C). This dynamic temperature difference change is captured by the Fresnel lens and focused onto the sensor.

  Alarm Trigger: The pyroelectric sensor converts this "radiation fluctuation" into an electrical signal. Only when the rate of change of this signal (i.e., movement speed) and its intensity (i.e., the magnitude of the temperature difference) meet a specific threshold will the detector send an alarm signal to the main unit.

• Key False Alarm Prevention Mechanism:

  To improve reliability, PIR sensors typically employ dual or quaternary pyroelectric sensors. The two sensing elements have opposite polarities; when a person passes through from one direction, two pulse signals, one positive and one negative, are generated. An alarm is triggered only when both signals are received simultaneously. This effectively filters out false alarms caused by small animals (single-point interference) or swaying curtains.

In summary, passive infrared (PIR) detectors are a very mature, low-cost, and low-power human movement detection solution. They are best suited for detecting "someone passing by" or "personal activity."

A contactless infrared sensor switch, also called a touchless switch or a gesture-activated switch, can be understood as a smart button that doesn't require actual touching; it's triggered simply by waving or pausing your hand in front of it.

Core working principle: Near-infrared reflection. Its core principle is "active emission, near-range reflection":

• Active emission: The switch contains an infrared emitter that continuously emits near-infrared light invisible to the human eye.
• Waiting for reflection: Simultaneously, an infrared receiver is placed nearby, constantly "watching" for any reflected signals.
• Trigger action: When your hand (or other object) enters its sensing range (usually 2 to 20 centimeters), the emitted infrared light is reflected back by the hand and captured by the receiver. Once the circuit detects a reflected signal, it immediately connects or disconnects the load.

This "contactless" feature makes its greatest value manifest in two areas: 1. Scenarios requiring extreme hygiene: In places with high hygiene standards, such as hospitals, food factories, and restaurant kitchens, waving your hand to open doors effectively prevents cross-infection.

• "Exit button" in access control systems: This is its most widespread application. Installing such a switch on the inside of doors in offices, apartment buildings, or homes equipped with electric locks allows for easy unlocking with a wave of the hand, offering convenience and a more high-tech feel than traditional mechanical buttons.