We present here the improved design and develop-
ment of optical sensor for non-invasive measurements of ar-
terial blood flow waveform. The sensor is based on a physical
principle of reflective photoplethysmography (PPG). As the
light source we used serially connected infrared diodes where-
as NPN silicon phototransistors were used as light detectors.
The electronic components were molded into square package
and poured with silicone. Such preparation produced an elas-
tic superficies that allowed excellent attachment of the sensor
on the skin’s surface. Moreover, a serial connection of infrared
diodes and phototransistors completely eliminated signal
artifacts caused by minor muscle contractions. The
sensor recording performances were examined at the
photoplethysmographic sites on three different arteries; the
commune carotid, femoral and radial and, on each site the
sensor demonstrated remarkable capability to make a consis-
tent, reproducible measurements. Because of the advanta-
geous physical and electrical properties, the new sensor is