What’s new in sensors for smart homes: Part 3

Air quality sensors have been measuring and monitoring outdoor air quality applications for many years. More recently, they have been used more frequently for indoor applications in smart homes and connect to the home’s Wi-Fi network. One of the more unique sensed items is radon. Similar to other harmful gases, people cannot see or smell radon, but long-term exposure to this radioactive gas is the top cause of lung cancer in non-smokers.

One manufacturer offers an air quality sensor for radon that also has a laser-based particulate matter (PM 2.5) sensor, a non-dispersive infrared (NDIR) carbon dioxide (CO₂) sensor, and an air pressure sensor (since changes in pressure impact radon levels) as well as sensing for temperature and humidity.

Figure 1. Indoor sensing of radon and 6 other parameters in a smart home can be easily accomplished today (Image: Airthings).

Other air quality sensors also measure PM10, gases like ozone, sulfur dioxide, nitrogen dioxide, and volatile organic compounds (VOCs). Based on the measured parameters, the unit can provide an air quality index (AQI) score with acceptable readings, making the homeowner and occupants more secure.

More unique sensors

Some of the other more unique newer sensor additions to smart homes have been used previously in other more stringent applications, including industrial, automotive, and commercial. These include noise, vibration, and pool temperature/pH sensors.

Noise sensor

Sensing noise — not specific sounds but the decibel (dB) level and its duration in a smart home can:

Provide an input in short-term rentals to alert owners of loud visitors.
Be used in conjunction with pet monitoring cameras
Provide an alert to crying children
Alert homeowners to avoid violating local noise ordinances

Vibration sensor

Depending on the number of sensed axes, an acceleration sensor (accelerometer) can measure vibration and, often, tilt and drop. The sensed vibration can monitor kitchen or bathroom areas for unwanted pet- or child-related activities involving food, delicate/expensive items, dangerous materials, and more. In the yard, a vibration sensor on a fence or gate can warn if a pet or child is trying to break out or get into a restricted space.

Pool temperature/pH sensor

Depending on what needs to be sensed to provide a more fulfilled life for the homeowner and their family, many new sensors (soil moisture, rainfall, water monitoring, sleep sensors, and more) can be added to today’s smart home. The final sensor for this blog installation is a pool temperature/pH sensor. For the homeowner lucky enough to have a pool, monitoring the temperature, the pH, and other aspects of the water in their pool can add even more enjoyment to their life.

Key aspects of smart home sensors

What accuracy is required for smart home sensors? The combined temperature/humidity sensor mentioned in Part 1 provides one answer. For one supplier’s product, where the temperature range is -20 °C (-4 °F) to ~60 °C (~140 °F), it has a temperature accuracy of 0.1 °C (0.18 °F). The humidity range is 1% to ~99%, with an accuracy of 2%. Other sensors’ accuracies could depend on the parameter, sampling intervals, initial calibration time, detection technique, and more.

The low cost of smart home sensors compared to sensors in industrial and automotive applications was discussed in Part 2. In fact, many of the sensors discussed in this article can be purchased from Amazon and cost about $20 to $40 — some lower and some higher, even much higher.

Another key aspect of many, if not most, of the newest sensors is long-lasting, battery-powered, wireless technology that easily connects the sensor to a network where automated activity or user monitoring can occur.