Checking one’s pulse is both simple and familiar: Press two fingers against the radial artery in the wrist and count the beats to determine heart rate. But while this act can indicate heart rhythm and strength of pulse, it reveals little else about a person’s health. Thanks to capacitive tactile pressure sensing technology, however, this most basic of medical procedures can now be leveraged to obtain more-insightful patient data.
As described in a recent blog post, the application of capacitive tactile pressure sensor arrays to the wrist has enabled the exploitation of pulse pressure measurement to quantify blood pressure measurement. High blood pressure affects one out of every three adults in the United States, according to the American Heart Association, and that number is only expected to increase.
One reason that tactile pressure sensing is so well-suited for this task is that it can handle the extremely low pressures that need to be measured; blood pressure is so slight that it is measured in millimeters of mercury (mm HG), with 1 mm Hg equaling roughly 0.02 psi. The highly sensitive nature of the capacitive tactile sensors allows them to detect and measure that low pressure accurately and quickly—much more quickly than, say, someone taking his or her pulse by hand.
That’s also part of what allows the technology to measure the entire pulse pressure wave and provide a detailed waveform. Where conventional pulse finders might be limited to reading the frequency of the beats, this waveform data can be analyzed to provide information on factors like arterial hardness, which can be an indicator of hypertension.
Of course, in order to work in practical terms, the tactile pressure sensors must also be durable enough to withstand being pressed against the wrist. And because they are not being used on a flat surface, the sensors must also be conformable—or flexible—enough to accommodate the contours and shapes of the radial artery and wrist.
In a real-world application of this technology, a Chinese company called JXJ Technologies sought out PPS’s PulseTact technology for a watch-like device designed to detect the physiological parameters of patients for health monitoring. The driving concept behind the jWotch was to create a device that collects pulse-waveform information and then sends that data to a cloud-based support system through which it could be monitored and accessed by healthcare providers.
Capable of taking pulse and blood pressure measurements, among others, the device offers several advantages over traditional blood pressure measurement methods that involve cuffs or chest straps, which can be vulnerable to signal loss. The lack of cumbersome equipment, in particular, is optimal for elderly patients. And the design of the product more-closely resembles a stylish accessory than a healthcare monitoring device.
In addition to being embedded in watch-like monitoring devices, tactile pressure sensors for pulse pressure measurement also lend themselves to technologically enhancing traditional Chinese medicine. Traditionally, three fingers are used to take a person’s pulse, and factors such as pulse velocity and width are considered. PPS is currently working with GE China to develop clinical systems that would help make Chinese pulse medicine more quantitative.