For hundreds of years, engineers have built sensors into systems and devices to gather information from the physical world. Sensors have done much to automate systems, make the world smarter and advance our way of life, but only recently have consumers engaged with sensor information in personal ways.
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The sensor industry is growing at a very healthy pace. “The IoT (Internet of Things) is impacting growth across many market sectors, including sensors, where the number of units produced and employed will exceed 35 billion units by 2018,” according to Semico Research & Consulting Group. Vendors are shipping discrete sensors, as well as combo sensors that incorporate more than one function.
New use cases for sensors are emerging all the time, and applications once considered futuristic are now commonplace. The smartphone, as the hub of most sensor applications for consumers, is bringing many of these capabilities home to us for our personal use.
The smartphone: a converged device for sensor applications
Smartphones have become such common platforms for sensor applications that in many cases, consumers no longer need traditional products such as cameras, navigation devices or even carpentry leveling tools.
Some smartphone applications combine information from multiple sensors to bring new contexts to the mobile experience. For example, advanced accelerometers and gyroscopes will open the door to market opportunities for convenient smartphone virtual reality applications. Fitness products and healthcare will become personalized with multi-sensor smartphones. It’s now possible to combine data from smartphone voice, motion, touch and location sensors to help Parkinson’s disease patients understand and manage their care. Most of the truly exciting opportunities probably haven’t even been thought of yet.
Single function, specialized devices
As the emerging IoT is proving, single-function devices are also transmitting personalized sensor data to us via our smartphones or other gateway devices.
Many consumers use smart home products, from baby monitors to kitchen appliances, in conjunction with smartphone applications for monitoring and control. In the sporting goods industry, manufacturers are embedding sensors into golf clubs, boxing gloves and other products that send the data to a smartphone or device to help analyze an athlete’s performance. We’ve all heard about contact lenses that detect blood glucose levels for diabetes patients and transmit the data wirelessly to the patient or healthcare provider. The emerging category of implantable biosensors is expected to further revolutionize health diagnostics and patient monitoring.
Enabling sensor applications in your designs
To ensure consumers can view and engage with data from sensor applications, the sensors must interconnect with one another and consume minimal energy. The device also must have a wireless communications link for data transmission.
Interconnections: Wired interfaces are needed to connect sensors with one another and with a sensor hub, microcontroller or application processor inside the device. Traditionally, designers have used Inter-Integrated Circuit (I2C), serial peripheral interface (SPI), universal asynchronous receiver/transmitter (UART) or simple general-purpose input/outputs (GPIOs) to interface sensors. The industry is now consolidating these approaches into MIPI I3C, a two-wire unified interface that can interconnect and manage sensors to provide system-level benefits in a broad range of mobile, mobile-influenced and embedded systems applications.
Maximizing power efficiency: Every little bit of energy saved in a sensor implementation helps conserve battery life. The goal for sensors is to operate at microwatt levels so a device, such as a fitness band operating on a coin cell battery, can function for a month or more. Even in a complex smartphone, which can operate at milliwatt levels, sensor implementations must minimize power consumption to help the handset maintain its charge for all-day operation.
Designers can use a low-power sensor hub, such as a microcontroller or application processor, to improve efficiency. The sensor hub consolidates and interprets inputs from various sensors. For example, it can average the raw data from a heart rate monitor to characterize a pulse rate over time. While designers can implement “sensor fusion” capability physically in a standalone chip or program it in the microcontroller, application processor or modem, many designers find that the standalone approach can reduce energy consumption.
MIPI I3C, which consumes a fraction of the energy compared to legacy interfaces, will also help minimize power.
Wireless connectivity: Developers need wireless connectivity to transmit information from the device to a hub or gateway, and increasingly, developers might want the device to connect wirelessly to a cloud application to facilitate sensor control and data storage and possibly to process the data. The type of connectivity used depends on the application. An IoT product will often use the Bluetooth low-energy features to connect to a smartphone. If the product is a smartphone or virtual reality device, it could use 4G LTE or, in the future, 5G. Some devices will use USB connections.
When selecting a sensor, make sure it is appropriate for the application, easy to integrate and minimizes power consumption. If you’re deploying multiple sensors in a device, make sure they are interoperable with one another.
Bringing information home from trillions of sensors
Experts in the sensor industry, led by the MEMS & Sensors Industry Group and the TSensors Initiative, are projecting that trillions of sensors will be connected in the coming years. The potential is remarkable and traces directly back to 2007, when Apple launched the iPhone and popularized sensor-based applications for handheld, connected consumer devices. Today, a typical smartphone has about 10 sensors, underscoring how personal sensors have become.
As the IoT evolves, many aspects of mobile device architectures, including sensors, will be used in mobile-influenced and embedded systems targeting non-mobile market segments. Automobiles, for example, are expected to become another platform for personalized sensor applications. As designers prepare for these opportunities, they’ll need techniques to interconnect the components, minimize power consumption and facilitate wireless connectivity. The technologies used in smartphones have paved the way for these opportunities and will provide the foundation for much of this work to come.
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