posted on 2024-02-01, 06:03authored byBijender, Shubham Kumar, Amit Soni, Rimjhim Yadav, Surinder P. Singh, Ashok Kumar
In the present global
context, continuous blood pressure (BP) monitoring
is paramount in addressing the global mortality rates attributed to
hypertension. Achieving precise insights into the human cardiovascular
system necessitates accurate measurement of BP, and the accuracy depends
on the faithful recording of oscillations or pulsations. This task
ultimately depends on the caliber of the pressure sensor embedded
in the BP device. In this context, we have fabricated a flexible resistive
pressure sensor based on reduced graphene oxide (rGO) and a polydimethylsiloxane
(PDMS) sponge that is highly flexible and sensitive. The designed
device operates effectively with a minimal bias voltage of 500 mV,
at which point it showed its maximum relative change in current, reaching
approximately 25%. Additionally, the sensing device showed a notable
change in resistance values, exhibiting almost 100% change in resistance
when subjected to a pressure of 400 mmHg and high sensitivity of 0.27
mmHg–1. After promising outcomes were obtained during
static pressure measurement, the sensor was used for BP monitoring
in humans. The sensor accurately traced the oscillometric waveform
(OMW) for distinct systolic blood pressure (SBP) and diastolic blood
pressure (DBP) combinations to cover a range of medical situations,
including hypotension, standard or normal, and hypertension. The values
of SBP, DBP, and MAP were derived from the sensor’s output
using the MAA technique, and the errors in these values concerning
the simulator and the traditional BP monitor follow the universal
AAMI/ESH/ISO protocols. Bland-Altman (B&A) correlation and scatter
plots were used to compare the sensor’s results and further
validate the proposed sensor. The sensor showed the mean and standard
deviation error in the SBP, DBP, and MBP of −0.2 ± 5.9,
−0.5 ± 7, and −0.9 ± 4.7 mmHg when compared
with the noninvasive blood pressure (NIBP) simulator. The pulse rate
(PR) was also calculated from the same OMW for the specified value
of 80 beats per minute (bpm) given by the simulator and reported a
mean PR value of ∼81 bpm, close to the reference value. The
findings show that the flexible resistive sensing device can accurately
measure BP and replace the existing sensors of BP devices.