Advancements in wearable blood pressure monitors

Engineers at the University of California San Diego have developed an adhesive ultrasound patch capable of measuring central blood pressure in deep veins or arteries up to 4cm below the skin. Central blood pressure is not the same as normal blood pressure, it monitors the blood pressure of the vessels which carry blood directly from the heart to major organs, and is considered to be a more accurate reading and also better at predicting heart disease.
This non-invasive device is made of a thin sheet of a silicone elastomer, and lots of small electronic components connected by island bridge structures, which are effectively spring shaped wires, each containing piezoelectric transducers. When a current passes through them, ultrasound waves are produced which get inside the skin and are able to record the diameter of a blood vessel deep inside the body. As blood pulses through it, the diameter changes and the reflected signals are translated into a waveform which represents a specific activity or event in the patient’s heart. The shape and features of the waveform can be analysed using appropriate software.
Sheng Xu, a professor of nanoengineering at the Jacobs School of Engineering, said: “By integrating ultrasound technology into wearables, we can start to capture a whole lot of other signals, biological events and activities going on way below the surface in a non-invasive manner. Right now, these capabilities have to be delivered by wires from external devices. If we want to move this from benchtop to bedside, we need to put all these components on board.”