From talking refrigerators to implanted heart monitors to trains that report seat availability, sensors are a vital part of the Internet of Things (IoT). In fact, you could make a good argument for calling it the “Internet of Sensors.” Most IoT devices include a sensor array, a microcontroller (MCU), Bluetooth or WiFi radio, and power management. Some devices also have a display or push-button inputs.

IoT_graphicIoT devices are focused on physical interfaces that use sensors and actuators, as opposed to the human interfaces of most computing platforms. IoT devices receive input through sensors that are typically miniaturized through MEMS technology. They send out information through wired or wireless interfaces to mobile devices and cloud-based servers. Sensor types include pressure, chemical, strain, and temperature, each with varying measurement frequencies and triggers. Communication connectivity involves varying intervals, distances, data rates, packet sizes, etc.

Most industrial devices are now smart, connected products with built-in sensing, processing, and communications capabilities. Much of the equipment that is remotely located includes embedded sensors that identify equipment problems and report them back to manufacturers through cloud software over the Internet, thus making them IoT devices. Sensors generate data, data produces knowledge, and knowledge drives action. Therefore, making sense of the data that those devices generate creates productivity improvements through equipment maintenance, inventory optimization, energy savings, and labor efficiencies.

According to ABI Research, the increasing adoption of IoT within industrial settings will result in a substantial growth of the number of connected devices, in particular control devices like programmable controllers (PLCs). It is expected that the number of connected industrial controllers will triple by 2020. This will produce an enormous strain on the existing infrastructure, both wired and wireless.

IoT Constraints: Power and Miniaturization

Regardless of the application, IoT devices are often located without easy access to power. This makes low power consumption one of the most universal constraints across the IoT space. IoT devices also require long lifetimes, further constraining power consumption. Bigger systems can afford µW – mW average powers, but millimeter-size devices need to make do with nW powers.

According to a team of researchers at the University of Michigan, “In low duty cycle systems, the sensor will be mostly inactive, reducing active power consumption and making standby power the dominant component. On the other hand, systems with high bandwidth requirements will have significantly higher power budgets with the radio as the dominant factor.”


Figure 1: IoT Sensor Properties and Power Constraints.

IoT device packaging requirements typically include miniaturization in the form of low-cost, good power dissipation (low power for the silicon portion), good RF shielding, and support for multiple RF standards, such as WiFi, ZigBee, or BTLE (Bluetooth low energy, aka Bluetooth Smart). As discussed in EDN, “Cavity-based solutions are popular when sensors are involved, especially when there are stimulus delivery requirements such as port holes in microphones. IoT packages must also be production ready, since waiting for a new custom package is often not an option due to time-to-market constraints. Finally, regardless of whether the solution is discrete or integrated, the footprint must be small.”


Figure 2. Common MEMS packages and die fabrication techniques that could be adopted for IoT devices.

IoT Constraints: Bandwidth

The IoT is also constrained by the Internet’s available bandwidth. The demand for WiFi and the transmission of mass quantities of mobile data is predicted to grow exponentially. By 2019, more than ten billion mobile devices will exchange 35 quintillion bytes of information each month. Add to that the countless desktop computers and computer-based equipment located in households, schools, government facilities, and throughout industry.

McKinsey reports that the IoT has a total potential economic impact of $3.9 trillion to $11.1 trillion a year by 2025. At the top end, that level of value—including the consumer surplus—would be equivalent to about 11 percent of the world economy.

IoT_economic_impactTo achieve this kind of impact, companies need to work with each other and with government agencies to overcome technical, organizational, and regulatory hurdles.

Let’s start with the glut of IoT data, much of which is not used:

  • On an oil rig with 30,000 sensors, only 1 percent of the data is examined. That’s because this information is used mostly to detect and control anomalies—not for optimization and prediction, which provide the greater value.
  • A fleet of 100 modern rail cars produces between 100 to 200 billion data points annually. Siemens is working with railways to create data teams to monitor the data that a train sends out, including information about what parts of the train have broken, what spare parts have been used, what spare parts are still available, what geographic regions it has traveled through (is there a hill that is notorious for causing problems?), and whether it’s near a service depot that has capacity to provide maintenance.
  • According to Deloitte, the primary challenge in chronic care is linking the devices so they can communicate reliably and securely. While in-home blood-glucose and heart-rate sensors, for instance, are widely available, they are rarely set up to export their data to a system that aggregates and shares information with all involved parties.

To handle the data, a network is needed that balances conflicting requirements, such as IoT device range, battery life, bandwidth, density, endpoint cost, and operational cost.

According to Gartner:

Low-power, short-range networks will dominate wireless IoT connectivity through 2025, far outnumbering connections using wide-area IoT networks. However, trade-offs mean that in many cases, network types will coexist.

For IoT applications that need wide-area coverage combined with relatively low bandwidth, good battery life, low hardware and operating costs, and high connection density, cellular networks don’t deliver. Wide-area IoT networks need to to deliver data rates from hundreds of bits per second (bps) to tens of kilobits per second (kbps) with nationwide coverage, a battery life of up to 10 years, an endpoint hardware cost of around $5, and support for hundreds of thousands of devices connected to a base station.

The first low-power wide-area networks (LPWANs) were based on proprietary technologies, but in the long term emerging standards such as Narrowband IoT (NB-IoT) will likely dominate this space.

Industrial IoT applications present an additional challenge in that they often require high data rates in order to transmit and analyze data in real time. Systems creating tens of thousands of events per second are common, and millions of events per second can occur in some telecom and telemetry situations. To address such requirements, distributed stream computing platforms (DSCPs) have emerged.

Other new technologies are being created to help the IoT become a self-sustaining network of sensors and devices that deliver valuable insight obtained from massive amounts of data:

  • Laminated multilayer busbars provide efficient and compact connections for propulsion, auxiliary, and other IGBT based converters in connected car and connected rail systems.
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