Novel applications of principles from the fields of physics and math have led to countless medical breakthroughs, ranging from the electrocardiogram to magnetic resonance imaging. We had the opportunity to speak with Harry Bullivant of UK-based The Technology Partnership (TTP) about a potentially disruptive gas-sensing technology called SonicSense that may be used for respiratory monitoring and capnography, among other applications.
Shiv Gaglani, Medgadget: What is SonicSense?
Harry Bullivant: SonicSense is a unique new approach to gas sensing which radically cuts costs, size and power consumption. The ultrasonic sensor uses patent-pending TTP technology to precisely measure the speed of sound in a gas to determine its composition.
We think the technology has great potential to disrupt a broad range of healthcare sensing applications such as respiratory monitoring, capnography, anaesthesia and COPD monitoring.
Medgadget: Can you describe how the technology works?
Bullivant: The sensor draws on TTP’s expertise in resonant acoustics and piezoelectric devices. Roughly speaking, the sensor measures the resonant frequency of a vibrating volume of air – imagine the note produced by an organ pipe. This frequency (or ‘note’) depends on the temperature of the air and its composition. Once we apply temperature compensation, we can determine the composition of a binary gas mixture. Additional bulk gas properties such as density can also be determined using the same sensor architecture if we want to evaluate more complex gas mixtures.
The current sensor models measures only 24 mm in diameter and 18 mm deep, but we expect the dimensions can be reduced to less than 5 mm. And with a simple, robust design and low power consumption of around 10 mW – compared to over 1 W for some sensors– our device is ideally suited to long-lifetime, battery powered applications.
Medgadget: How did you come up with the idea for SonicSense?
Bullivant: We are often being asked to create new technologies and are constantly investigating new areas of physics, mathematics, and engineering. In this case, we had developed and commercialized a novel micropump technology with a medical device company. During that process, we realized that a related physical phenomenon could be used to monitor gas composition… and SonicSense was born.
Medgadget: Who should use SonicSense? Are there any other markets that you are looking at?
Bullivant: The range of applications of SonicSense is very broad and we’re having some great conversations across healthcare. SonicSense is particularly useful for companies wanting to reduce the cost of existing gas sensors, or investigate radical new products enabled by its low cost. For example, imagine the clinical benefits of dramatically reducing the cost of capnography (monitoring exhaled CO2) to the point where it is as ubiquitous as pulse oximetry.
Whilst healthcare is an important market for us, unsurprisingly there are lots of other gasses that need sensing. It is always surprising how many different and diverse applications come up in our discussions.
Medgadget: Why is this better than competing products?
Bullivant: Current infrared gas sensors for carbon dioxide can cost over $100 and paramagnetic sensors for oxygen around $200. By contrast, we believe our devices will cost between $5 and $10 each in volume production. Most competing low-cost sensors are based on a chemical reaction similar to that of a battery and like a battery they only last for a short period of time – often less than a year. SonicSense measures the acoustic properties of the gas rather than a chemical reaction avoiding the issues of drift and lifetime.
These advantages are possible because of our deep understanding of the underlying physics and an intelligent approach to design. Of course, this is only possible because of the great team of scientists and engineers we have at TTP!
Medgadget: What is your background in medical tech?
Bullivant: TTP is based near Cambridge, UK and we’ve been developing medical devices and technologies for over 25 years. In that time we’ve helped commercialise over 40 inhalers and drug delivery devices, sometimes incorporating technologies invented at TTP. A good example is the eFlow nebulizer for PARI Gmbh – a TTP droplet generation technology enables very precise control of drug delivery. This ensures that as much drug as possible reaches the deep lung making a huge difference to the time taken to give the patient their dose as well as helping PARI to move from a plug-in table-top device to a battery-powered portable.
We’re now seeing a trend for smarter, integrated medical devices. These need to incorporate sensors and communications, whilst retaining the same functionality and form factor as existing ‘dumb’ devices. Squeezing everything in can be a real challenge!
