Improving hemoglobin estimation accuracy through standardizing of light-emitting diode power

Abstract

Nowadays, hemoglobin monitoring is essential during surgeries, blood donations, and dialysis. Which are normally done using invasive methods. To monitor hemoglobin, a non-invasive hemoglobin meter was developed with five fixed light-emitting diode (LED) wavelengths at 670 nm, 770 nm, 810 nm, 850 nm, 950 nm and controlled using an Arduino Uno embedded development board. A photodetector with an on-chip trans-impedance amplifier was utilized to acquire the transmitted signal through the finger using the photoplethysmography (PPG) principle. Before the standardization of LED power, we had tested the designed system on fifteen subjects for the five wavelengths and estimated the hemoglobin with an accuracy of 96.51% and root mean square error (RMSE) of 0.57 gm/dL. To further improve the accuracy, the LED power was standardized and the PPG signal was reacquired on the same subjects. With this, the accuracy improved to 98.29% and also reduced the RMSE to 0.36 gm/dL. The designed system with LED power standardization showed a good agreement with pathology results with the coefficient of determination R<sup>2</sup>=0.981. Also, Bland–Altman analysis was used to evaluate the designed system and it showed good agreement between the two measurements.

The effect of contact pressure on photoplethysmography

“…Recording the intensity of reflected and transmitted light through the measured location, pulse wave signals could be obtained, which consists of arterial pulses period of each heartbeat, and plenty of biometric information can be detected [2]. The most typical application of PPG monitoring is transmission-mode finger pulse oximetry [3], whereas reflected PPG acquisition positions are more adaptable for wearable devices [4]. In recent years, research interest in PPG applications has grown beyond oximetry to encompass diabetes, hypertension, atherosclerosis, coronary artery disease, coronary heart disease, heart rate, and blood pressure monitoring [5].…”