Though the SARS, MERS and Ebola outbreaks each resulted in loss of life, they were restricted to a relatively small number of countries. COVID-19 has proved far more challenging to contain. No part of the world has managed to avoid the virus and its impact, making it the most significant global pandemic in over a century. Since the first cases emerged in China back in December 2019, there have been over 35 million global COVID-19 cases to date. Though lockdown measures over the spring and summer slowed the infection rate in some areas, there has since been a resurgence.
Curbing the Spread of the Virus with Remote Monitoring
Experts agree that contact tracing and self-isolation of individuals who are infected with COVID-19 can go a long way in helping to reduce the spread of the virus. To that end, remote symptom monitoring has played a critical role in the fight against COVID-19. Remote monitoring is a reliable way of tracking symptoms of isolated individuals, either while they are waiting for a test or while their symptoms subside. It can provide peace of mind to the patient as physicians can still monitor their condition. It also allows for clinical resources to be allocated to the most severely infected patients. There is no question that the global healthcare infrastructure is stretched. When you add in the impending strain of the regular Northern Hemisphere flu season, it is more important than ever to minimize the unnecessary use of healthcare resources.
There are also some logistical advantages to remote monitoring of symptoms. In this scenario, regularly-updated temperature data can be automatically stored in the cloud, removing the need for laborious manual data entry—and eliminating the possibility of human error.
What Technology Is Available Today?
NXP’s NHS3100 NTAG® SmartSensor is an IC optimized for the accurate temperature monitoring and highly-secure logging that can enable the remote monitoring use cases described above. It collects temperature information from a body-worn sensor patch. The data is then uploaded securely into the cloud via NFC, where clinicians monitor it and can communicate treatment options via a web interface if needed.
The sensor IC can measure temperature with an accuracy of 0.3°C across an operational range of 0°C to 40°C. It has a measurement resolution of 0.02°C, picking up even the smallest skin temperature changes. It also exhibits strong stability over its operational lifespan. It has a high computing and data storage capacity, with a 32-bit Arm Cortex-M0+ processing core, plus 32kB of embedded flash memory resource.
Each IC has a unique ID combined with a unique cryptographic key to ensure high levels of security. The cryptographic key also safeguards against hacking of data across the entire system. No patient information is stored in the patch. Instead, data is uploaded directly to patient records in the cloud. The URL contains a generated hash that ties the measurement to a specific monitor patch. The only way to compromise this would be to physically damage the monitoring unit (which would then be visible).
Figure 1: NHS3100 functional block diagram. Source: NXP
Data Collection Methods
The NHS3100 has two possible data collection methods for fever monitoring:
- With the 'Momentary' method, a patient taps the patch with their smartphone to get an update on their temperature. This is a passive arrangement, with the smartphone providing the energy needed to take a temperature reading. The patch, therefore, doesn't need to incorporate a battery cell. Each time a measurement is taken, the acquired data is uploaded directly onto a cloud server through the cellular network.
- The 'Logging' method uses a similar type of patch, but this time a battery is included. The patch's sensor takes periodic temperature measurements—usually every 10 minutes (this is configurable). The temperature data is then stored until there is an opportunity to upload it to the cloud. This method has the advantage that everything is done automatically. It does not depend on the patient remembering (or needing to be prompted) to take the reading. The addition of a battery leads to a slightly higher cost and it also calls for a dedicated smartphone app.
Figure 2: Examples of NHS3100-based temperature monitors. Battery-run (left) and passive (right). Source: NXP (left); RFID (right).
In both cases, the mechanism relies on measuring skin temperature rather than internal body temperature. Using an algorithm, it is then possible to extrapolate the body temperature figure. Some form of thermal barrier is required to prevent ambient heat from affecting the results obtained, so the patch has an insulation layer covering the sensor.
Several OEMs are already providing late-stage prototypes of wearable temperature monitoring devices to their customers using these ICs.
Figure 3: A patient measuring her body temperature with the “Momentary” method. Source: NXP / IDENTIV
Remote monitoring provides a way of identifying potentially infectious individuals, who can then isolate to ensure they don’t pass on the virus. It also does its part to alleviate the pressure on our healthcare infrastructure. Monitoring solutions that leverage NFC technology’s numerous operational benefits will have a vital role in empowering societies to combat the COVID-19 virus.