No longer limited to simply passing an electrical-measurement signal, smart sensors collect, convert, and process data and offer machine-to-machine communication. This trend has blurred the traditional definition of an edge device and given rise to the notion of the extreme edge utilising smart sensors.

Smart Sensor Architecture

There are three important aspects of smart sensor design- data acquisition, data processing, and data communication. At a minimum, a smart sensor comprises a sensor element, a microprocessor, and a communication technology. It also incorporates software-defined elements that provide data conversion, digital processing, and communication to external devices and the cloud. A smart sensor can support various sensing technologies in more advanced cases, handling and delivering multiple measurement values.

Figure 1 provides a generic example of a smart sensor's architecture that contains the most common functions. The signal chain in a smart sensor node starts with the core sensor function. Many of these produce low-level analog outputs that require precision signal conditioning to preserve the critical information they gather. Signal conditioning functions include sensor excitation, signal amplification, anti-alias filtering, low-pass, and high-pass filtering, linearisation, and an often overlooked but an essential feature—isolation.

Figure 1: Smart Sensor Architecture

Several types of devices can be used as processing units-Microcontrollers, SoC and FPGA. The choice of each depends on the complexity and functionality of the smart sensor. Processing units integrated into smart sensors are much more sophisticated, incorporating excitation sources, high-resolution analog to digital (A to D) and D to A converters, general-purpose discrete I/O, fast architectures, math support, and low-power modes. The embedded intelligence continuously monitors the discrete sensor elements, validates the provided engineering data, and periodically verifies sensor calibration and health. The essential difference of the smart sensor from the integrated sensor with embedded data-processing circuitry is its intelligence capabilities (self-diagnostics, self-identification, or self-adaptation (decision-making)) functions). Using a processor-based system inside sensors can potentially bring significant benefits over simple sensor designs - better accuracy, reliability, fault detection, advanced power management, flexible design cycle, and additional features, etc.

Smart sensors can be connected via a range of different interfaces using non-contact, optical/inductive connections or 'wirelessly' via passive or active radio technology. The choice of interface depends upon the requirements and demands, such as the power supply, range, and miniaturisation. The communication/storage function supports data staging and connectivity with IoT cloud services (encryption/security, storage, and analytics). Eventually, the communication module manages the communication between the smart sensor system and external devices (local, remote, or monitoring stations).

Smart Sensor Ecosystem

A differentiator of the smart sensor is its role in the broader information and analytics ecosystem. Integrating smart sensors throughout the supply chain can decrease operating costs, increase asset efficiency, and improve demand planning. Transmission standards such as WiFi, Bluetooth, NFC, RFID, and others are then used to communicate this data to other sensors, controller devices, centralised management platforms, or distributed computing platforms for data aggregation and analysis (Figure 2).