Smartphone App Allows for Rapid HIV Testing

A new biochip attached to a smartphone has demonstrated in a proof-of-concept study that it can be used to detect HIV in a drop of blood from a finger prick and display the results within 10 seconds.

Rachel McKendry, PhD (pictured), a professor of biomedical nanotechnology at University College London, in the UK, described implications of the development to MD Magazine. "The speed and accuracy of the tests will help to support patients and front-line health-workers by widening access to testing outside of hospital settings, and cut lengthy wait times," she said.

The customary testing process, based on enzyme-linked immunosorbent assays (ELISAs) and polymerase chain reaction (PCR) require the resources of centralized laboratories. "Inherent delays occur between taking samples, conveying them to the laboratory, waiting for results to come back and subsequent follow-up appointments," McKendry and colleagues pointed out in their report.

McKendry explained that the new "ultra-rapid" biochip is based on shear horizontal surface acoustic wave (SH-SAW) technology, and is anticipated to be inexpensive and widely available as SH-SAW filters and sensors are already incorporated into smartphones.

"The breakthrough is that SAW technology requires no complex microfluidics, sample labels, amplification steps or was steps, and can detect biomarkers within seconds," McKendry said.

McKendry and colleagues distinguished their product from other recently developed point of care tests, which utilize lateral flow technology and typically take 10 to 20 minutes to provide results.

"This exceeds a typical doctor's appointment necessitating changes to patient pathways within a clinic with additional on-costs and staffing implications," they wrote. "It is also notoriously difficult to interpret a faint lateral flow test line by eye, particularly for non-experts (eg, self-testers)."

The ultra-rapid biochip was developed under a grant from the Interdisciplinary Research Collaborations (IRC) in the UK by the University College London program, I-Sense, which self-describes its purpose, "to engineer a new generation of early-warning sensing systems to identify disease outbreaks much earlier than before, using self-reported symptoms on the web and mobile phone-connected diagnostic tests."

The I-Sense biochip contains proteins on its surface to capture a biomarker of HIV from a drop of blood, such as the anti-p24 antibody or the p24 antigen. The change in surface mass and viscoelasticity from the captured antibody or virologic antigen is then detected in the phase change of the SH-SAW between input and output electrodes.

The prototype system used in the proof-of-concept study comprised a hand-held control box, the disposable biochip and a mobile device (laptop or smartphone) to analyze, display and transmit results. A more advanced version in development reconfigures these elements with the biochip mounted on a disposable cassette resembling a USB stick and the results sent to a smartphone app via either cable or Bluetooth.

"We are working with clinical teams in the UK and South Africa to explore the use of mobile phone-connected HIV tests, which link to online prevention and medical care," McKendry said. "The secure online app could allow a person testing to get their results and care, and potentially access to HIV drugs, from within their local community."

The proof-of-concept report of the ultra-rapid smartphone-connected HIV test was published online September 20 in the Nature journal, Scientific Reports.