Making Sensors of the World

How many sensors do you think you own? Let’s start with your thermostat. It’s simple, right? You might guess one or two, and if you owned a 2[SUP]nd[/SUP] generation Nest you’d be wrong. It comes with a light sensor, heat sensor (in addition to temp), microphone, carbon monoxide sensor, smoke sensor, and occupancy sensor. Also, you might have a home security system – so, more sensors. I have a Blink Home security system and it comes with sound, motion and temperature on each camera unit, in addition to the camera itself.

Next is your phone. They most often come with GPS, compass, accelerometer, multiple temperature sensors for internals and ambient temp, and proximity sensor to tell where if your ear is against the screen. Phones also have fingerprint and heart rate sensors, cameras, microphones and more. The tallies I have seen online suggest there are around 20 sensors in many phones.

We are just getting started. I have an app for my MacBook that shows the internal hardware sensors. These include voltage, current and temperature for many individual components of the system. Batteries are instrumented, as well as GPU’s, the external case, and of course the CPU. MacBooks also have light sensors, cameras, microphones and more.

I’ve already lost count and now we are getting to the good stuff – cars. I own an older car but it has a bevy of sensors for running the engine and reducing pollution – The include temperature sensors, O2 sensors, pressure for emissions, and a variety of others. It also has motion and sound for the alarm. The antiskid system has rotation sensors on the wheels as well as accelerometer and gyroscope. Oh, did I mention the GPS yet.

According to an article written by Sidense, cars today have 60 to 100 sensors, and smart cars will easily reach 200. The automotive industry alone will use 22 billion sensors per year by the year 2020. Stop and consider that for a second. The article entitled “Sensors Everywhere” by Jim Lipman and Andrew Faulkner is filled with interesting information. For instance, with the requirements for so many automotive sensors, the market for them will grow from $22B in 2016 to $37B in 2022.

The article also outlines a lot of the other applications that will be using sensors, now and in the future. Indeed, the Internet of Things would be pretty useless without sensor technology. You might as well move it all back to mainframes in a server room if you do not intend to gather physical or electromagnetic information from the device operating environment.

Sidense is interested in sensor technology because implementing sensor based designs for connected devices and systems requires non-volatile memory. There are a lot of different varieties of non-volatile memory that are used based on system requirements. One Time Programmable (OTP) NVM is uniquely suitable for an important subset of these needs. The underlying technology relies on a single transistor bit cell that is fabricated using a standard layer stack-up. This is nice because it does not add any extra fabrication steps or costs. The small size of the bit cell is attractive, as well as are the area savings.

The memories can be programmed before distribution or programming can be done in the field using an integrated charge pump or external rail voltage suitable for write operation. Because there is no stored charge – the bit is programmed with a physical change to the thin oxide of the 1T bit cell – the data retention is excellent. The Sidense OTP-NVM is very rugged and suitable for extreme environments – making it ideal for automotive and other applications with wide ranging temperatures and physical stresses.

The Sidense article outlines some of the use cases for OTP-NVM. Sensors need to store calibration data, and while this data rarely changes, it’s nice to have provisions for updates. OTP-NVM is an easy and effective way to handle this requirement. Security is another ripe area for OTP-NVM. The data in the bit cells is nearly impossible to hack. Side channel attacks are also thwarted due to OTP-NVM characteristics that the article discusses. OTP-NVM is used to store unique device ID’s, crypto keys, system configuration and feature keys, among other things. Because larger blocks of OTP-NVM can simulate re-writeable memory, with a limited number of rewrites, it can be used for secure boot code storage, adding to root of trust in critical systems.

Clearly the applications and prevalence of sensors will only increase. Areas where they can be used not even mentioned here include smart buildings, medical, smart cities, and defense. There is high value in adding sensors to many areas of our lives and our world. Hopefully this technology can be used to increase efficiency and improve our quality of life. Regardless new and more sensors are a certainty. If you want to read the full article by Sidense on the applications of OTP-NVM in sensors, look on the Sidense website.