Implantable biosensors – is the future continuous monitoring?
30 August 2016
With an ageing population and squeezed budgets putting increasing stress on the healthcare system, many policy makers see greater personalisation as the route to more effective and efficient health services.
Devices implanted within us, which require minimal human action in providing continuous information about chemicals in our bodies, could be a central component in deliveri ng this personalisation. But how far along the pathway to clinical application are these technologies and what are the barriers standing in their way?
Implantable biosensors include a range of devices, but they all work on the same principle. A biological sensing element - which interacts with the substance being monitored - is coupled to a transducer that converts the signal produced by their interaction into one that can be more easily measured and quantified. A third element displays the results in a user friendly way. As platforms for analysing biomarkers - molecules that can be objectively measured and evaluated as indicators of normal or disease processes - the potential of biosensors hinges on the development and validation of these biomarkers.
Meanwhile, advances in nanomaterials and wireless technologies are leading to huge leaps in the development of implantable biosensors. There remain a number of important technical issues to address, such as improving the lifetime of the sensor and ensuring not only that the biosensor is tolerated by the body, but also that its presence and interactions do not in themselves affect the accuracy of its readings.
Implantables for managing chronic conditions
Driven by need and demand from the diabetic community, the traditional market pull for biosensors has been for blood glucose measurement. An unobtrusive implantable biosensor, such as Senseonics’ Continuous Glucose Monitoring (CGM) system (which received CE Mark approval in May 2016), could further improve the management of chronic conditions such as diabetes by removing the non-compliance factor associated with portable and wearable devices. For example, some diabetes patients may stop taking regular glucose readings due to the pain and time associated with finger-prick tests; with an implantable this obstacle is removed. Of course, even with the continuous monitoring from an implantable, the user might not act on results; the human body has a multitude of inbuilt sensors, such as pain, which humans frequently fail to act upon promptly. To overcome this ‘human’ challenge, some implantables could be paired with a continuous drug delivery method, such as a fully implantable artificial pancreas - the ultimate aim for diabetes patients.
Aiding personalised healthcare
Speeding up the development of personalised drugs is another area where implantable biosensors could have a significant impact. Implantable biosensor chips, developed by the Swiss Federal Institute of Technology in Lausanne (EPFL), can measure in real time more than one metabolite in the human body, along with pH and temperature. These devices could allow researchers to track the effects of candidate drugs on the body precisely, allowing them to determine more quickly whether a drug should continue in clinical development.
Implantable biosensors may one day aid the development of personalised cancer therapies by measuring the rapid, highly localised and transitory changes of certain biomarkers that influence a tumour’s response to radiotherapy and chemotherapy treatment. There is even a biosensor chip technology in the early stages of development which in the future could be implanted to detect specific DNA mutations in the blood that indicate disease, even before any clinical symptoms appear. Biosensors also offer scope to improve post-operative care with dissolvable pressure sensors for the brain, and sensors monitoring infection and inflammation following hip implants, for example.
Harnessing the data
Continuous monitoring of biomarkers will capture vast amounts of data, raising several challenges:
- For this data to make a real difference to patient care there need to be mechanisms for the efficient and secure collection, storage and sharing of this information with the relevant parties. Building public trust around how health services manage patient data will be critical to the successful use of biosensors in patient care.
- Producing evidence of clinical validity will be essential and it will need to be understood whether the data generated can be used for a diagnosis or treatment decision on its own, or as is more likely, what other information in addition is required to reach a clinical decision.
- The huge quantity of data generated will inevitably include a considerable amount of irrelevant information. Predictive algorithms that separate the noise from relevant, actionable data will be needed. Interfaces that can deliver clear, understandable information and guidance to the user will also be essential.
Is the future implantable?
The power of implantable biosensors to improve patient care and disease management is exciting, but there are technological barriers to overcome, as well as a need to develop validated biomarkers. When, inevitably, implantable devices do enter mainstream use, they may have a disruptive effect; it will be necessary to rethink care pathways, what decisions lie with the patient and what will be overseen by clinicians.
In development of personalised drugs, implantable biosensor chips may have great potential, and it will be interesting to see the results of a proof of concept trial for a schizophrenia drug in which they are being used. However, in the management of chronic conditions and detection of disease there may be more effective – and cost effective – approaches already in place. It is also not yet known whether being continuously monitored by devices that cannot be easily removed will be generally acceptable to the public; if not, their use will certainly be impeded.