Driving with any detectable level of THC (Delta-9-tetrahydrocannabinol - Cannabis’ psychoactive component) in saliva is illegal in Australia. Research shows that, despite 'being tested for THC while driving' being the top concern among patients, the majority of Australia’s medicinal cannabis patients are likely driving with detectable levels. The leading reason; patients have no accessible way of assessing their saliva for THC. Currently, saliva tests are inaccurate, unaffordable single-use tests which can cost up to $40. This project aimed to design a physical intervention that would enable patients to cheaply and accurately measure THC and assess whether they are eligible to drive.
Delta Sens presents an innovative approach to saliva testing that allows medicinal cannabis patients to measure the concentration of THC in their saliva cheaply and accurately. It eliminates the need for single-use tests and instead offers a reusable, portable electrochemical saliva tester that interfaces directly to the user's phone, via the Delta Sens app, allowing them to assess their eligibility to drive at any time. By using disposable screen-printed electrodes as both the sensor and testing site, Delta Sens is able to capture and analyse a saliva sample at a fraction of the cost, with far greater accuracy and functionality.
Fundamentally, Delta Sens was designed to improve the quality of life of Australia’s medicinal cannabis patients. Given that 2 in 3 Australians drive to work, the benefit it offers to patients also has potential social and economic flow-on effects as it better allows for patient engagement in society and the workforce. By shifting the focus from single-use saliva tests to a reusable electrochemical testing device, the environmental footprint of saliva testing is radically reduced. If realised, Delta Sens could also improve road safety and may have implications for legislation and driving laws including facilitating the adoption of concentration-based testing.
Delta Sens is designed with simplicity and portability at its heart; it has no battery, Bluetooth, or on-board interface. It instead utilizes a powerful technology already in everyone's pocket: by connecting directly to the user's phone for power, data transfer, and to interface through the Delta Sens app, Delta Sens maintains a compact, portable design. To measure the concentration of THC in a saliva sample, Delta Sens uses voltammetry, an electroanalytical method that measures the electric current as the electrical potential is varied. THC antibodies present on the testing strips bind to THC metabolites, changing the potential and current, allowing for the measurement of THC concentration. Delta Sens provides a wealth of information to users, including accurate readings of real-time THC salivary concentration. With enough results, Delta Sens can accurately map a user's individual THC metabolism and predict the time to total THC elimination from saliva. With predictive elimination time, Delta Sens can suggest and schedule a re-test in the event of a positive result. Through the Delta Sens app, patients can also use metabolism mapping and historical data to plan their dosing schedule, ensuring they test negative when they need to drive.