Product Marketing Manager, Novelda

Kjetil Meisal's profile picture

Respiration Monitoring Enabled with Radio Frequency Tech

There is so much hype around the Internet of Things technology, which many people view as simply a communication backbone with a lot of sensors. Some people even call it the Internet of Sensors. A vast number of sensor technologies now exist — IR, capacitive, ultrasonic, and microwaves — but they are typically designed for specific tasks such as detecting presence, motion, speed, or distance. Take, for instance, respiration rate, a medical vital sign that can provide insight into a person’s general state of health and quality of sleep.

Respiration rate and respiration patterns are considered vital indicators for many medical conditions and they require accurate, dependable monitoring data. Respiration rate — the number of breaths a person takes per minute — is best measured when a person is at rest. However, respiration rate alone provides limited information; it's respiration patterns that reveal valuable data for detecting sleep anomalies and other medical conditions.

The first generation of sensor technologies to provide accurate breathing pattern data has mostly been directed at professional monitoring solutions. These either measure airflow in and out of lungs, which is a rather invasive technique, or they use an electromechanical approach that requires an elastic strap tightened around the person’s chest. Then, there are acoustic technologies that require the device to be connected to the monitoring subject's neck.

These methods require physical connection of a sensor to the body and often cause discomfort to the monitoring subject, which can affect a person's breathing and, in turn, result in incorrect respiration pattern data. Novelda AS has developed its XeThru monitoring technology to overcome these limitations and provide a sensor solution that is practically invisible in the room and to the monitoring subject.

Novelda’s XeThru sensor technology is based on an ultra-wideband (UWB) impulse radar implementation. It provides a non-contact monitoring solution that is highly accurate, has an effective range up to 2.5m, and is capable of capturing breathing patterns and frequency without being blocked by obstacles like clothing while also being low cost and easy to use. XeThru technology uses radio waves rather than infrared, ultrasound, or light, and allows sensor modules to “see through” a variety of objects including lightweight building materials, duvets, and blankets to provide non-contact sensing at a range of several meters.

respirationpattern A view of respiration pattern tracking

Why XeThru Sensor Technology

The growing level of consumer consciousness about health and well-being has led to the creation of a plethora of healthcare and fitness monitoring devices. However, while these fitness trackers are capable of measuring breathing rates, sleeping with a monitoring device connected to the body is uncomfortable for most people. Next up, there are advanced sleep monitors that use non-contact technology and are based on either capacitive sensor units placed under bed sheets or continuous wave (CW) Doppler radar solutions that monitor respiration from the bedside.

However, capacitive sensing units need to be installed in the bed, or they require a special mattress. Likewise, while radar technologies are a logical choice for monitoring systems that are non-intrusive, the CW-based radar approach falls short because it only provides phase information and is unable to measure or differentiate in terms of distance. That means they lack the ability to differentiate between normal and shallow breathing.

Moreover, historically radar implementations have been costly due to the use of discrete components built on an expensive ceramic substrate. They also need to operate at higher power levels to achieve the necessary signal-to-noise ratio (SNR). And the presence of a high-power radar on the bedside would most likely also be a concern for many potential users. By understanding the limitations posed by capacitor Inspiration Kit is designed for evaluation, proof of concept, and prototyping. Inspiration Kit is designed for evaluation, proof of concept, and prototyping. sensor units, CW radars, and other health wearables, Novelda was able to rethink the approach required to achieve a solution that can operate at a reasonable distance with the following key attributes:

  • Low cost
  • Low power
  • Safe and easy to use
  • Easy integration in end-products

Inevitably, both cost and power factors steered Novelda toward a sensor based on an integrated circuit implemented as a system-on-chip (SoC) design using a standard CMOS process. Novelda's patented XeThru sensor technology uses digital signal processing to accomplish the lossless pulse integration for delivering high SNR. The module consumes less than 400mW power and remains unaffected by dust, smoke, moisture, darkness, or any other airborne debris it may encounter.

inspirationkit Inspiration Kit is designed for evaluation, proof of concept, and prototyping

A Complete Sensor System

The UWB impulse radar technique emits and samples signal pulses to achieve highly accurate distance measurements determined by the time differences between the transmitted and received signals. The unobtrusive sensors carry out real-time tracking of respiration patterns by detecting presence just from a person’s chest movement while breathing. In addition, the adaptive smart sensor module can detect respiration regardless of a person’s position provided they are within the detection zone.

Novelda has implemented UWB impulse radar as an SoC solution built around its proprietary and patented XeThru sensor technology. It employs digital signal processing and spread spectrum technologies to recover the return signal so that it can operate at much lower power levels than conventional radar. The use of spread spectrum communications also enables UWB impulse radar to coexist with other RF systems without causing interference.

The standalone module is a complete sensor unit available as a single PCB solution with all the key ingredients of an OEM unit. It comprises of PCB antennas, the XeThru SoC, power management, and a low-power ARM Cortex-M4 microcontroller as the processing unit. The module, designed to operate as a standalone sensor, can also serve as a development platform for respiration monitoring, presence detection, and distance measurement apps. Standalone modules and easy-to-use development kits simplify the application development of sensing products like breathing monitors.

Novelda is targeting its sensing technology at home automation, sleep monitoring, baby monitoring, and elderly care applications. The company offers the XeThru Inspiration Kit for developers so they can evaluate the performance of the sensors using the software and carry out module configuration, visualization of sensor data and data capture for later analysis. The XeThru development kit comes with sensor module and interface board for connection to a personal computer.

Novelda's sensor modules are ready to be integrated into end-user monitoring products. Developers can build their application layer on top of the sensor module and integrate XeThru technology with their application software without having to learn RF design, signal processing or antenna interface. In other words, a very short time-to-market with a significant saving on technology investment.