Over the past 10 years, we've seen quite an array of fitness-related smart technology, ranging from step counters to heart rate monitors. Recently, engineers from the University of California Berkeley were able to develop a device that is capable of monitoring a person’s core body temperature from their ear.
The device is a 3D-printed sensor that is worn on the ear, nicknamed the “Earable.” The Earable is the first wearable smart device that is capable of monitoring core body temperature in real time. In addition, the device also functions as a hearing aid and could potentially have a wide variety of use as a vital sign sensor.
The Earable. All images used courtesy of the American Chemical Society
Being able to monitor a person’s core temperature can be very useful as an indicator of various health issues. While other wearable sensors that measure body temperature do exist, such as wristbands, these traditional sensors rely on the measurement of skin temperature. While practical for many reasons, this information can differ greatly from a body’s real core temperature due to things such as the temperature of the environment.
Knowing this, the research team set out to develop a wearable device that would not only be accurate but also would avoid the normally intrusive procedures of measuring a person’s core body temperature. The least intrusive of the traditional processes was to use an infrared sensor to measure the temperature of one’s eardrum, which led the team to create a device using similar technology.
Designing a 3D-Printable Device
The team started by using a 3D-printer to create a flexible disc made from a stretchable polymer. To provide circuit functionality and flexibility, the discs were printed with channels to inject a liquid interconnect in place of wiring.
Images from the device assembly process. Figures a-d show how the channels are printed to create the circuit.
After printing, the device is layered with components ranging from an infrared sensor with microprocessors to a Bluetooth module to transmit data to a separate device for viewing. Since the device is covering the ear, it is also equipped with bone-conduction hearing aid comprised of a microphone to gather sound, an actuator to convert sound to vibration, and a potentiometer to control volume.
The device was tested on various subjects in different physical states as well as environments of varying temperatures.
The results showed that, unlike the traditional skin temperature sensors, the Earable is unaffected by these external conditions.
Following their work, the researchers stated that the size of the Earable was limited by the resolution of their printer and the size of the components they were able to obtain. This means we could definitely see size reduction in the future.
The research paper did not explicitly state the team’s plans for future development but did mention the potential applications they were looking towards.
“While only a bone-conduction hearing aid and tympanic sensor were demonstrated in this work, sensors for measuring other vital signals such as heart rate, pulse oximetry, and EEG may also be integrated into the 3D-Printed Earable device platform for comprehensive long-term, real-time monitoring of an individual’s health and physiological state.”
The original research paper was provided by the American Chemical Society. See the full paper here.