Renesas Electronics

Unobtrusive Smart Patch Revolutionizes Monitoring and DiagnosisThe need to monitor the vital signs* of patients infected with Covid-19 not only created a risk of secondary infection but was also stressful for patients

*“Vital signs” include heart rate, respiratory rate, body temperature, and oxygen saturation.


As the Covid-19 pandemic continues to rage around the world, doctors are recommending that the vital signs of those infected with the virus be monitored, so that caregivers are aware of any changes in their patients’ condition. However, with each additional observation points becomes more stressful for the patient and an increased risk of passing the virus onto health workers. Hoping to change this, major semiconductor manufacturer Renesas Electronics (hereinafter Renesas) was working on a reference design for a low-cost, slimline medical patch that would enable patients’ vital signs to be monitored remotely.


Creating a Slimline Medical Patch that Supports Remote Monitoring

The slimline medical patch that Renesas was developing could be attached to various points on the body, including the forehead, arm, and wrist, enabling accurate real-time monitoring of body temperature. In order to monitor the patient’s body temperature continuously, a temperature sensor is mounted on the bottom of the device, which makes contact with the patient’s skin. When the patient places their finger on the biosensing IC on the top of the patch, the patch also measures the heart rate, respiratory rate, and oxygen saturation. The patch can also transmit these information to a smart phone over BLE 5.0 wireless communication.

Power Challenges

Operating a medical patch of this nature requires a battery that is compact and slimline, while at the same time powerful enough to support wireless communication. It was also vital that the device could withstand bending moments, so that it would remain attached to the patient’s arm when they bent their arm or moved. Additionally, environmental considerations meant that the battery had to be reusable. To create a slimline and unobtrusive medical patch, the development team needed a battery that satisfied all of these requirements.

Main Issues

  • The device needed to be compact and slimline, while remaining powerful enough to support BLE.

  • The device had to be flexible in order to fit snugly to the body.

  • A single-use battery would create disposal issues and be environmentally unfriendly.