A Molecular Touchscreen

Lead Research Organisation: University of Cambridge
Department Name: Engineering

Abstract

Point-of-care testing (POCT) represents 15% of the of the in-vitro diagnostics market and is predicted to reach 38 billion USD market size by 2022. A key driver for growth is the demand for faster, portable and inexpensive testing for a high number of end users. Mobile phone diagnostics bring new potential to this field on a global scale as rapid, widespread testing requires a non-invasive reader system, calibrated quantitative outputs and the means to collate and compare data. As of 2018, there are 4.6 billion mobile phone users worldwide, rounding up to 67% by 2019 with an uptake in developing countries.

This project aims to explore how wet assays can be integrated with component technologies in the phone with a vision to create a new personal biosensor platform. For example, we will specifically investigate the potential of linking to the electrical properties and measurements made in touchscreen technologies and design a device that responds to (i) changes in ion concentration and (ii) the presence of targeted biomolecules near the screen surface to provide a measurement of personal health. It is anticipated that the approach will scale to tackle broader diagnostic challenges in developing countries where rapid, inexpensive tools with embedded computing and communication capabilities are needed to take on healthcare and agricultural challenges.

The research methodology is based on four steps:
- Research into the full range of sensors available within the phone platform, including ability to access advanced electrode and device structures.
- Identifying suitable physical and chemical model systems to enable a wet assay to integrate with phones. The model systems will begin as simple electrolyte sensors and move to more complex molecular label designs.
- Study quantitative readouts to understand limits of detection and interpretation of results in the context of biosensing.
- Prototyping of hardware links to enable the sensing platform, including a paper study into the scale-up potential to help with delivering impact after the PhD programme.

The project is carried out together with industry partners such as M-Solv Ltd. By uniting latest manufacturing technologies with the most recent advances in affinity protein engineering, DNA technology and cell proliferation analysis, the project combines a variety of academic disciplines, all represented in the EPSRC's strategic portfolio of highly relevant research areas:
- Clinical technologies
- Sensors and instrumentation
- Manufacturing technologies

These areas of biosensing and microscale material manufacturing are highly relevant to the CambridgeSens strategic network, and communication of this research will enable broader impact through other fields and industries, such as water quality associations, the food industry, agriculture and air pollution detection.

Planned Impact

Outputs from the CDT will include both research outputs and the training of cohorts of highly qualified, interdisciplinary postgraduates, expert in a wide range of sensing activities.
WHO WILL BENEFIT: Immediate beneficiaries of the research outputs will be industrial consortium partners in the CDT (currently Alphasense, Rolls Royce, Shell, Cambridge Display Technologies, Nokia, NPL and others). They will help steer the training and research programmes of the PhD students and CDT outputs will feed directly into their research programmes and future strategy. Other interested UK companies will also be able to benefit via outreach activities of the CDT (workshops etc) and recruitment from the CDT's student pool. It is anticipated that both national and international policy makers and regulators, e.g. in the area of environmental monitoring, medical diagnostics, etc. will also benefit from the research output of the CDT in terms of setting regulations commensurate with state-of-the-art sensor technologies emanating from the CDT consortium. Potential public-sector beneficiaries include the NHS (sensing advances for medical diagnostics, patient monitoring etc), Museums and Galleries (new sensing techniques applied to conservation of artworks), Armed and Security Services (new sensing techniques and approaches for threat detection and mitigation, contraband and drugs-of-abuse detection - direct beneficiaries will be the Home office and other government agencies, with whom discussions are taking place), Transport (sensor networks for traffic management, pollution control). Beneficiaries of the sensor-training aspect of the CDT will be the afore-mentioned companies, both in the UK and abroad (e.g. EU), who will be able to employ the highly-trained, interdisciplinary postgraduates produced by the CDT, who will be skilled and experienced in a wide range of sensing aspects and technologies. It is anticipated that some of this postgraduate cohort will also remain in academia and hence will implant their sensor knowledge and expertise in Universities outside Cambridge, to the overall benefit of the UK higher-education sector.
HOW WILL THEY BENEFIT: Sensing technologies contribute to an estimated £200bn global market. Thus, there is a very significant opportunity for increasing the UK competitiveness and share in this large market as a result of the new technologies and research outputs emanating from the CDT, coupled with the uniquely qualified and trained researchers emerging from the CDT who will be able to develop new products and forge new markets in this area, both via SME and large corporations in the UK. Thus, there is a very considerable potential economic upside to this activity, in terms of wealth generation and employment in this sector. In addition, there are appreciable potential societal health and well-being benefits from this Sensors CDT. Sensing is central to medical diagnostics and patient monitoring. Future developments in personalized healthcare monitoring, e.g. networked home-monitoring of patients with chronic illnesses will improve patient outcomes and quality of life, and concomitant cost savings for the NHS. There is exciting potential in combining health care sensing (and indeed many other types of sensing) with mobile phone and wireless technology improving coverage, cost, and speed of response. Better and novel sensors will reduce downtime of transport infrastructure due to targeted preventive maintenance; novel sensors will be less intrusive, but more robust, in security measures for public places, etc. The postgraduate cohorts emerging from the CDT will have been trained in a wide range of activities in addition to sensor science and engineering. They will have been exposed to courses in entrepreneurship, and so will be equipped to start up new ventures. Students will also have greater awareness and experience at teamwork, both through activities in the CDT itself, and during secondment to industry.

Publications

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Description We are investigating the use of mutual projected capacitive touchscreen technologies for mobile bio sensing applications. Two thirds of the world's population possesses a mobile device based on capacitive touchscreen technology. This includes many people in developing countries. In the medical industry, point-of-care sensing technology is one of the fastest growing sectors. We aim to combine both. Our device is composed of a nanometre thick layer of optically transparent indium tin oxide (ITO) layer deposited on both sides of a glass panel. Electronically conductive horizontal and vertical lines are formed by laser ablation of the ITO deposit. The created electrodes are then covered with a micrometre thick Parylene polymer layer for protection and robust cleaning. We apply an electric potential in between the top and bottom ITO electrodes of the dielectric glass and measure the electric capacitance. The electrostatic fringe field that is build up during measurements reaches out through the Parylene film on top and interacts with electrically polarisable materials in proximity. The amount of interaction depends on the material properties such as electric permittivity, conductivity and ion mobility and induces a change in the detected capacity. Electrodes can be driven individually. By sequentially activating the nodes of the electrode array one can extract the spatial position of a detected change on the panel. We test liquid electrolyte samples to detect changes in ionic concentrations. Electrolytes are contained in human body fluids like blood and sweat, but also in drinking water. Unhealthy composition of body electrolytes can indicate diseases such as chronical kidney dysfunction. The sensor shows a linear response to the ionic concentration in the electrolyte across a range of 0 to 200 uM for static capacitance measurements of sodium-, magnesium-, calcium- and potassium-chloride. At higher concentrations the sensor saturates. Increasing the Parylene thickness from 1 um to 5 um allows for increased dynamic range at a loss of sensitivity for low concentrations and yield a worse limit of detection (LoD). To differentiate between types in the sample we evaluate the impedance response to different perturbation frequencies using electric impedance spectroscopy (EIS). Currently, we are using computer simulations to further manifest our findings. Next steps include the detection of an ion selective pattern in the signal by changing the surface properties of regions on the screen.
Exploitation Route If we succeed in selectively measuring ion concentrations in human body fluids with existing touchscreen hardware there is a sudden impact for the mobile bio sensing industry not only in developed, but also in low-income countries as the approach is cost effective and achievable with little effort and knowledge. Further research would go into measuring specific disease markers using this technology.
Sectors Environment

Healthcare