FEAT RE MEDICMEDICAL ELECTRON C FEA ATURE


ONICI S


BLOOD PRESSURE MONITORING DEVICES utilise advanced tactile sensors


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measurement all but the most invasive, intra-arterial techniques deficiencies that can lead


hile there are many methods for performing blood pressure ,


to inaccurate or suffer from


inconsistent results. Even the standard blood pressure cuff used by healthcare practitioners has significant limitations. The latest generation of thin, conformable tactile sensor arrays promises more precise, accurate measurement of pulse pressure


waveform. Advancements will be realised in both a clinical setting, for applications such as improved artery location and pressure measurement, and in a


consumer setting for next-generation wearables such as fitness bands and smart watches that will measure more than just heart rate.


Although broadly accepted and widely used, studies have shown that manual blood pressure measurement can include errors as large as 10mmHg for systolic and diastolic pressures. In particular, the procedure is sensitive to physician hearing acuity as well as their overall diligence while preforming the procedure. Pulse oximeters, which have been traditionally used to mon oxygen saturation and pu


lse rate, are itor blood


now being used to monitor blood


pressure as well. These devices pass two wavelengths of light through the body to measure the changing absorbance information that is then used to infer blood pressure.


While both these options have merits, neither approach meets the accuracy and repeatability standards of the lead


organisations such as the Association for the Advancement of Medical


Instrumentation (AMMI) and British Society of Hypertension.


Instead, a more direct measurement of the pulse waveform is gaining interest, one that enables ambulatory, non- invasive blood pressure measurement without cuffs by utilising advanced capacitive tactile sensing technology. Using capacitive tactile sensors, blood pressure can be measured using sophisticated arrays that map the


pressure above the artery. This can range froma number of discrete measurements to a large, dense array of hundreds of


26 FEBRIUAR 201 26 FEBRIUARY 2017 | ELEC ELECTRONICS


ve, thiin,, conformabletact tactile sectile sensorsw lps willl playake clinical devialde icevces that m asurebloodpr ssuree


re key roe n th eyrolle i in thenex ext evces thatmeasure blood pressure says Pressure Profile Systems resaysPressureProfile Sy


xt generation of Systems


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Pressure Profile Systems (PPS) is a specialist in capacitive tactile sensing solutions. To build its tactile array sensors, the company arranges the electrodes as orthogonal, overlapping strips. A distinct capacitor is formed at each point where the electrodes overlap. By selectively scanning a single row and column, the capacitance at that location, and thus the localised pressure, ismeasured.


ART Capacitive tactile


Figure 1: Capacitive tactile


Figure 1:


pressure sensing is well- suited for blood pressure measuring as capable of handling extremely low pressures


pressure sensing is well- suited for blood pressure measuring as capable of handling extremely low pressures


elements. These sensors, in direct


proximity to the artery, deliver a detailed pulse waveformthat is then used to determine blood pressure and pulse information, including other parameters such as arterial hardening.


To conformto the contours of the human body and other curved surfaces, tactile pressure sensors are designed to be integrated into a variety of soft, flexible materials.


Figure 2: Capacitive tactile sensors use arrays that map the


Fi 2


pressure above the artery


AR ERIAL RTERIAL LINEINE LOCATORS ATORS


Another promising application for capacitive tactile sensors is arterial line placement, a common, but difficult, procedure performed in a clinical setting. Overall, arterial line insertion is considered safe, with a rate ofmajor


complications below 1%. However, insertion of an arterial catheter is an invasive procedure and complications can occur. In fact, an accidental needle-stick of a physician in the U.K. ultimately became the stimulus for a grant fromthe Scottish government to seek a safer, more reliable method of inserting arterial catheters. Through PPS U.K., in partnership with the University of


Strathclyde in Glasgow, Scotland, set out to develop a device to simplify arterial localisation and make it safer.


The device utilises tactile sensor arrays in a conformable material that is worn over the clinician’s index and middle fingers. The tactile sensor identifies the location of the pulse, and indicates the location using LEDs and a needle guide to facilitate needle insertion. The device also protects the clinician’s fingers against needle-stick injuries.


Today, the holy grail of blood pressure monitoring is for consumer wearables such


Currently,most are li as smartwatches and


heart rate, butmany


are already developing mited tomeasuring fitness bands.


next generation devices with wristbands capable of taking blood pressure, pulse and other key arterialmeasurements. Capacitive tactile pressure sensing


technology is starting to enable a new wave of healthcare products based on non- invasive arterial pressuremeasurement.


www.pressureprofile.com T: info@pressureprofile.com


Pressure Profile Systems www.pressureprofile.com


/ ELECTRONICS ELECTRONICS BLOOD PRESSURE MONITORING DEVICES


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