New York, Aug 11: Researchers have found that a smartphone-based diagnostic test technology could perform lab-grade medical diagnostic tests that typically require large, expensive instruments.

The researchers at the University of Illinois at Urbana-Champaign in the US have developed a handheld spectral analyser that attaches to a smartphone and analyses patient blood, urine or saliva samples.

In a study published in the journal Lab on a Chip, the researchers demonstrated that the spectral transmission-reflectance-intensity (TRI)-Analyser costing $550 could make a smartphone do the tests as reliably as clinic-based instruments that cost thousands of dollars.

"Our TRI Analyser is like the Swiss Army knife of biosensing," said Professor Brian Cunningham.

"It's capable of performing the three most common types of tests in medical diagnostics, so in practice, thousands of already-developed tests could be adapted to it," Cunningham said.

Cunningham's team used the TRI Analyser to perform two commercially available assays -- a test to detect a biomarker associated with pre-term birth in pregnant women and the PKU test for newborns to indirectly detect an enzyme essential for normal growth and development.

Their tests results were comparable to those acquired with clinic-grade spectrometer instrumentation, according to the study.

"The TRI Analyser is more of a portable laboratory than a specialised device," said Kenny Long who is lead author of the research study.

Among the many diagnostic tests that can be adapted to their point-of-care smartphone format, Long said, is an enzyme-linked immunosorbent assay (ELISA), which detects and measures a wide variety of proteins and antibodies in blood and is commonly used for a wide range of health diagnostics tests.

The system is capable of detecting the output of any test that uses a liquid that changes colour, or a liquid that generates light output (such as from fluorescent dyes).

The TRI Analyser operates by converting the smartphone camera into a high-performance spectrometer.

Specifically, the analyser illuminates a sample fluid with the phone's internal white LED flash or with an inexpensive external green laser diode.

The light from the sample is collected in an optical fiber and guided through a diffraction grating into the phone's rear-facing internal camera.

These optical components are all arranged within a 3D-printed plastic cradle.

The TRI Analyser can simultaneously measure multiple samples by using a microfluidic cartridge that slides through an opening in the back of the cradle.

This ability to analyse multiple samples quickly and reliably makes the Analyser suitable for patients who lack convenient access to a clinic or hospital with diagnostic test facilities or for patients with urgent health situations requiring rapid results, the researchers said.

Smartphone-based diagnostic tests could replace labs