In this tiny sensor roundup, we will look at three different sensors that demonstrate the ever-present drive toward small, low power sensors in a world where electronics are ever decreasing in size.
Sensors have many practical applications, ranging across almost every industry under the sun. And, as we see a push towards smaller device form factors across almost every industry, sensors are also being reduced in size. In this article, we will look at three examples of incredibly small sensors and their practical applications.

 

IBM Fingernail Sensor

While many sensors are miniaturized in their construction (such as the use of reduced feature size in the silicon), others such as this fingernail sensor designed by researchers from IBM have taken advantage of AI and wireless technology to use wearable devices (such as the Apple Smart Watch) to process sensor readings.

The strength of fingertip grip is a good metric for diseases such as Parkinson’s which was the main aim of the IBM but after further research IBM have also recognized that fingertip strength can be used for other measures including heart health and cognitive abilities. To measure fingertip strength small strain gauges are attached to the nail of the finger and the readings from the strain gauge are wirelessly transmitted to an Apple Smart Watch and from there, AI software processes the data to determine correlations.

Image courtesy of IBM

According to IBM, one hurdle of electronics mounted to the skin is adherence (supergluing a sensor to skin is not an appropriate method for a multitude of reasons), but using the fingernail overcomes these issues. Unlike skin, nail is solid and often much stronger than skin, does not move around, and allows for a more permanent solution as nail is not shed nor grows too fast. The other major advantage of using nail instead of skin is that diseases such as Parkinson’s are almost always seen in the elderly whose skins is too fragile for reliable sensor mounting. The use of AI allows for the sensor to not only record information but also recognize the environment of the individual who is wearing the sensor. When combined with AI, the sensor data can be used to look for minute changes in defection from the nail which may include involuntary movement as well as gradual reduction in strength.

 

"World's Smallest" Gas Sensor from Nanoz

When it comes to gas sensors, Nanoz definitely takes the prize for the world's smallest gas sensor, measuring just 1.8mm x 1.8mm and with a height of only 0.45mm.

Based on metal oxide technology, the sensor is not only incredibly small but it is also able to detect a multitude of gases, including but not limited to CO2, CO, CH4, BTEX, and NO2.

Nanoz claims the gas sensor is the least energy-hungry metal oxide device on the market, the most reliable in time, and the least expensive to manufacture. These characteristics make the Nanoz sensor suitable for mass-production mobile and IoT applications, which could see everyday users gaining the ability to better monitor the environment around them using their smartphone.

 

Image courtesy Nanoz

While such integration of sensor technology has obvious advantages for engineers and workers in industrial applications, the act of integrating such sensors into everyday smartphones could be game-changing in personal safety. Users could use their smartphones as either backup smoke detectors should the main detectors fail or as a portable warning device for gas leaks.

 

Diminutive BMA400 Accelerometer for Wearable Applications

The BMA400 is a 12-bit accelerometer that is housed in a minute IC package measuring just 2mm x 2mm x 0.95mm. With low noise capabilities, the BMA400 draws an incredibly low amount of power while in sleep mode (800nA) while being able to output data at a user selectable range between 25Hz and 800Hz.

Combine these specs and what do you get? An accelerometer that's highly suitable for mobile and wearable devices.

Image courtesy of Bosch

The accelerometer is capable of measuring acceleration in three different planes with an offset of ±80mg, measurement ranges of ±2g, ±4g, ±8g , and ±16g, and a temperature coefficient of ±1mg/K. The BMA400 also has a number of built-in features including activity recognition (running, walking, etc), change in activity, orientation, tap/double tap, two general interrupts, and a 1kB FIFO buffer. With both SPI and I2C interfaces and an operation voltage between 1.7V and 3.6V the BMA400 is useful for IoT and mobile applications with its low power performance, miniature 12-pin LGA package, and many embedded features.

 

Year over year, the mantel of "tiniest [x] sensor" is passed from component to component. Manufacturers consistently research new semiconductor materials, packaging, and programming environments to make sensors smaller and smaller to match industry trends. Are you working on projects that need small sensors? What's your experience with space-constrained designs? Share your thoughts on shrinking sensors in the comments below.

 

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