New research from the McKendry group at UCL, published in Digital Medicine, reports a pilot clinical study using a shear horizontal surface acoustic wave (SH-SAW) biosensors based on low-cost components found in smartphones to diagnose HIV in 133 patients.
The study builds on research published in Scientific Reports in 2017, which showed promising developments towards a smartphone-connected diagnostic tool that can detect HIV infection within seconds. The device comprises of a disposable biochip, a pocket-sized control box reader developed by OJ-Bio, and a mobile device to analyse display and transmit results.
The importance of connected diagnostic tools for HIV
Early detection of HIV plays an important role in containing outbreaks, however currently available tests require complex lab equipment, highly trained staff, and long wait times for results.
“Today, around half of those who infected with HIV worldwide are unaware of their status, and linkage to care remains a challenge,” says Dr Valérian Turbé, Postdoctoral Research Associate in i-sense at UCL.
“The development of connected diagnostic tests opens up the potential for consumer electronics to cut lengthy test waiting times, giving patients on the spot access to treatment and supporting timelier public health interventions to prevent disease.”
Currently available rapid tests for HIV are typically analogue and carry the risk of being misread. These tests are also not connected and therefore there is no electronic data capture with the risk of potential data loss or errors in transfer.
The clinical study
“This clinical study shows encouraging results for a highly accurate, cost effective test reader that is able to produce rapid results, while requiring low sample volumes,” says Dr Eleanor Gray, Postdoctoral Research Associate in i-sense at UCL.
Samples from 31 patients with HIV and 102 healthy volunteers were tested using the SH-SAW biosensors. All positive results were recorded in 60 seconds using the electronic reader; faster than current tests which often require longer than 10 minutes to perform and cannot be run within the typical time of a GP appointment in the UK.
The advantage of SH-SAW biosensors
This study builds on previous work using SAW biosensors, by:
- improving the biochips to better cope with variations in sample volumes and reducing variations in results
- requiring a smaller sample volume to make it less invasive for those who find it difficult to produce large amounts of blood
- using inkjet printing to remove variation in chip preparation steps, meaning results are more consistent in comparison to manually prepared tests
- expanding to detect multiple HIV biomarkers to increase the accuracy and reliability of the test
The SH-SAW biosensor were benchmarked against leading commercial rapid HIV tests to compare for performance and proved comparable to tests currently being used in the UK.
The SH-SAW biosensors also provide electronic test readout, unlike currently available lateral flow tests, and therefore avoid the risk of misinterpretation of results. The device is also economical for mass production, costing approximately ca. $1.50 per disposable biochip
“The characteristics of these tests closely align with the World Health Organization’s target product profile for upcoming HIV rapid tests and has the potential to transform testing, particularly for under-resourced and hard to reach populations,” says Prof Rachel McKendry, Professor of Biomedical Nanotechnology at UCL and Director of i-sense.
“These tools and technologies allow HIV testing to take place outside of a traditional healthcare setting and can empower patients to take control of their own healthcare.”
The SH-SAW biosensors also adhere to the target product profile for HIV self-tests set out by PATH, which recommend tests to be user-friendly, simple to use, low cost, and not require interpretation of results.
“This work lays the foundations for a promising future of digital diagnostic technologies that combine the benefits of rapid HIV tests and smartphone capabilities, such as electronic data capture, location services, and wireless connectivity, allowing increased access to testing and care” says Professor McKendry.