and the theoretical maximum flow in a
normal coronary artery. Pressure sensors
help check for the seriousness of arterial
blocks, inform health practitioners if surgical intervention is required, and measure
the success of a surgery if it is conducted.
Choosing the right sensor
Fundamental to choosing the right sensor
is its ability to deliver the highest degree
of precision, durability and performance.
Arguably, this is exacerbated in the
medical devices field where measurements
are not only conducted in highly complex
environments, but the outputs directly impact the delivery of quality care to ensure
human life does not hang in the balance.
As a result, device manufacturers must
have confidence in the sensor provider
when working with companies regarded
for high reliability and near flawless quality. Scalable, value-added manufacturing
capabilities may be another consideration
in choosing to work with a sensor provider
that not only offers components but complete sensor connectivity.
Product flexibility is also key to ensure
device compatibility. For example, in measuring blood oxygenation (SpO2), device
manufacturers benefit from choosing a
sensor with the ability to provide red
LED wavelength tolerance up to 660 nm
± 2 nm, and which offers an emitter with
multiple IR LED wavelength choices:
660 nm, 880 nm, 905 nm and 940 nm. In
addition, SpO2 sensors (Figure 2)—offered
as either reusable or disposable—should
not only be manufactured to ensure maximum patient comfort but be latex-free and
biocompatibility tested in meeting industry
How A Blood Oxygenation
On extremities such as a finger, toe or ear.
• Reusable finger clip SpO2 sensors
• Durable soft silicone boot reusable
• Lightweight disposable SpO2 sensors
Within the SpO2 sensor, light emitting di-
odes shine red and infrared light through
the tissue. The blood tissue and bone at
the application site absorb much of the
light. However, some light passes through
the extremity, and a light-sensitive detec-
tor opposite the light source receives it.
In operation, the sensor measures the
amount of red and infrared light received
by the detector and calculates the amount
absorbed. Much of it is absorbed by
tissue, bone and venous blood, but these
amounts do not change dramatically over
short periods of time. The amount of arterial blood does change over short periods
of time due to pulsation (although there
is some constant level of arterial blood).
Because the arterial blood is usually the
only light-absorbing component which is
changing over short periods of time, it can
be isolated from the other components.
The amount of light received by the
detector indicates the amount of oxygen
bound to the hemoglobin in the blood.
Oxygenated hemoglobin (oxyhemoglobin
or HbO2 absorbs more infrared light than
red light. Deoxygenated hemoglobin (Hb)
absorbs more red light than infrared light.
By comparing the amounts of red and
infrared light received, the instrument can
calculate the SpO2 reading.
FIgure 2. TE Connectivity’s SpO2 Pulse-Ox-imetry offers a single-use, disposable
sensor solution for prolonged monitoring
scenarios or environments in which
cross-contamination is a concern.
Figure 3. The MEAS Finger Clip Sensor
Platform is designed to fit adult fingers
of various sizes.