This innovative technology platform is newest effort to measure biomarkers without the need for the invasive specimen collection techniques used in medical laboratory testing

Pathologists and clinical laboratory managers interested in how new technologies are transforming certain well-established clinical practices will be interested to learn about the latest research breakthroughs in pulse oximetry, a common procedure used to measure the oxygen level (or oxygen saturation) in the blood.

Pulse oximetry is considered to be a noninvasive, painless, general indicator of oxygen delivery to the peripheral tissues (such as the finger, earlobe, or nose). For decades, PO has been ubiquitous in the hospital. Now, because of recent advance, this field is poised for a paradigm shift away from simple monitoring devices to advanced products capable of connecting patients to electronic systems that continuously gather data and notify caregivers when values become critical.

A group of bioengineering doctoral students at the University of California Berkeley (UC Berkeley) have invented an inexpensive Band-Aid-style oximeter that uses red and green light to non-invasively monitor pulse rate and oxygen level in blood. While this device could revolutionize pulse oximetry monitoring in healthcare settings, the technology might also be applied to measuring other useful biomarkers as one approach to eliminate invasive specimen collection.

Organic Oximeter Attaches to Any Area of the Body Like a Band-Aid

Typically, pulse oximeter sensors are composed of rigid, silicon-based materials that constrict movement and placement. “There are various pulse oximeters already on the market that measure pulse rate and blood-oxygen saturation levels, but those devices use rigid conventional electronics, and they are usually fixed to the fingers or earlobe,” stated Ana Arias, Ph.D., a UC Berkeley Associate Professor of Electrical Engineering and Computer Sciences who headed this research team, in a UC Berkeley News Center report.

Her team’s wearable organic optoelectronic sensor device uses an organic, or carbon-based, electronic design that is thin, cheap and flexible like a Band-Aid. It can be attached to a finger, arm or anywhere on the body to accurately measure pulse and blood-oxygen saturation.

a pulse oximeter sensor

Engineering students at UC Berkeley have created a pulse oximeter sensor composed of all-organic optoelectronics that uses red and green light to accurately measure pulse and blood-oxygen saturation. The red and green organic light-emitting diodes (OLED) are detected by the device’s organic photodiode (OPD). The inventors suggested that this technology platform might be integrated into wearable activity trackers and/or used to monitor other body biomarkers without invasive specimen collection. (Image and caption copyright Yasser Khan/UC Berkeley.)

Accuracy of Organic Prototype Comparable to Conventional Oximeter

In a study comparing this prototype to conventional oximeters, the device measured pulse rate and oxygenation with errors of 1% and 2%, respectively, noted a December 10, 2014, Nature Communications paper.

Conventional pulse oximeters use light-emitting diodes (LEDs) to send red and infrared light through the fingertip or earlobe to detect oxygen saturation. Sensors measure the amount of light that gets through to the other side, noted the UC Berkeley News report. Oxygen-rich blood is bright because it absorbs more infrared light, while oxygen-poor blood is darker because it absorbs more red light. The ratio between the two wavelengths reveals the amount of oxygen in blood.

Arias’ research team, which included doctoral students Claire Lochner, Yasser Khan and Adrien Pierre, used red and green light to produce differences in blood hues comparable to how conventional oximeters use red light and infrared light to distinguish high and low levels of oxygen in the blood.

uc berkeley grad students organic pulse oximeter prototype

Pictured above (left to right) are Claire Lochner, Yasser Khan and Adrien Pierre, the UC Berkeley graduate students who assisted in development of the organic pulse oximeter prototype. (Photo copyright Berkeley Graduate News.)


How It Works

The student scientists explained that the device uses green (532 nm) and red (626 nm) organic light-emitting diodes (OLEDs) with an organic photodiode (OPD)—a semiconductor device that converts light into current—sensitive at specific OLED wavelengths. The sensor’s active layers are deposited from solution-processed materials via spin-coating and printing techniques.

Using a solution-based processing system, the researchers deposited the green and red organic LEDs and the translucent light detectors onto a flexible piece of plastic. By detecting the pattern of fresh arterial blood flow the device can calculate a pulse.

The organic oximeter sensor is interfaced with conventional electronics at 1 kHz. To determine accuracy, the device’s acquired pulse rate and oxygenation level were calibrated and compared with a commercially available oximeter.

“We showed that if you take measurements with different wavelengths, it works, and if you use unconventional semiconductors, it works,” said Arias in the UC Berkeley report. He also noted that the flexibility of organic electronics allows them to easily conform to the body.

Disposable and Cheap Enough to Use a New One Every Day

Arias pointed out that unlike convention oximeters, which are composed of relatively expensive components that must be disinfected after each use, “Organic electronics are cheap enough that they are disposable like a Band-Aid after use.”

This research project received funding support from the National Science Foundation and FlexTech, a health IT consulting firm based in Holland, Minnesota.

Given the high volume of PO procedures done daily and yearly in the U.S., pathologists and clinical laboratory managers should not be surprised that these researchers were motivated to improve existing technology and create products that reduce cost, improve accuracy, and that are easier for caregivers and patients to use.

Imagine how different hospital, urgent care and physician office visits would be if PO could be done simply by putting a Band-Aid-style device on the finger of the patient, then observing the results. As with many of these research innovations, it will take more time to conduct clinical studies and obtain clearance from the FDA to bring such diagnostic devices to market.

Further, it will be interesting to see if researchers can target other useful biomarkers in the body—some that are currently measured by medical laboratory tests—and measure them in vivo by the use of similar wearable organic optoelectronic sensor devices that don’t require invasive procedures to collect specimens for testing.

—Patricia Kirk

Related Information:

All-Organic Optoelectronic Sensor for Pulse Oximetry

All-Organic Optoelectronic Sensor for Pulse Oximetry

Organic Electronics Could Lead to Cheap, Wearable Medical Sensors

Band-Aid Like Disposable Wearable Pulse Monitor Is Here! 

Organic Blood-Oxygen Sensor Can Be Stuck on Like a Band-Aid

Medical Devices Optoelectronic Sensors in Medical Applications