OXIMETER MODULE
(spO₂ MONITOR)

Continuous blood gas monitoring is essential in critically ill patients in ICUs as well as other patients with cardio-respiratory complications. It necessitates withdrawing of blood samples from the patient periodically every 10 minutes to half an hour. In view of the invasive nature of this procedure there is a trend to monitor the same non-invasively from the fingertip of the subject employing optical absorption properties of the blood for the past two decades.

Transmission characteristics of oxy-haemoglobin and reduced haemoglobin in the visible and infrared regions of electro-magnetic waves show that oxy-haemoglobin gives maximum transmission at 650nm and reduced haemoglobin at 850nm. Also at 805nm, the transmission co-efficient of oxy and reduced haemoglobin is nearly equal. Therefore, the assessment of blood volume changes in the fingertip using photo transmission plethysmography at 650 and 805 nm can be used to the relative concentration of oxy-haemoglobin and total haemoglobin. 

The Oximeter Module (spO₂ monitor) developed at BARC employs infrared and red light emitters with a common photo sensor mounted on a clip, which can be attached to the finger. The photocurrent generated in the photo-sensor is detected and processed to obtain blood volume changes corresponding to 650 and 805nm. These blood volume changes are further processed to obtain the oxygen saturation percentage of the blood. This module can be integrated with available Patient Monitors or can be used as a standalone instrument with a microcontroller and a display unit. 

Specifications

Principle : Light absorbtion properties of the Red Blood Cells Sensor : Photo diode Range : 0% to 100% Accuracy : 1% Resolution : 0.1% Input : ±12V, +5V DC & Control signals from Microcontroller Output : Red & IR signals for Microcontroller

Applications

Oximeter Module (spO₂ Monitor) is used in ICUs, the recovery rooms and during surgery for monitoring the oxygen saturation percentage of the blood.

• Electronic assembly facility.

• Test equipment for measuring voltage and current

             i) 4 ½ digit DVM with 100 mV resolution.
            ii) 100 MHz, 5 mV Sensitivity storage oscilloscope.

• Skilled manpower : Qualified Biomedical/ Electronic Engineer with 3-4 years
  experience of testing analog and digital circuits and of using medical instruments on
  patients. One experienced tradesman for wiring.  

• Computer Engineer for interfacing this unit with microcontroller & personal computer/Patient Monitor and for developing the necessary software.

• Provision to import some component if not available locally.

• Facility for calibration.