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Increasing the quality of our lives, as much as their duration, is an active area of technology innovation and investment. Known as Lifelong Health, seemingly small actions can have big impacts on our bodies and wellbeing for decades to come.

As a mechanical and systems engineer, it is fascinating to see how I can use my skills and experience to complement one of the most precise mechanical systems on the planet. As discussed in my colleague's blog, we wanted to investigate an area of ‘change’ with age to both shed insights on the details of the ‘change’ and to explore how technology can help.  

We focused on the menopause and investigated the use of a ‘device’ to provide relief for women from hot flushes (or hot flashes as they are known in the US). The device could take the form of a wrist watch to combine functionality with discretion.

The initial goals

The starting statement was simple: can we design a watch which provides a rapid cooling effect? This was expanded with the following to give us something to work with:

  1. Comparable size and weight to a smart watch - by baselining against existing similar products in the field we are able to quickly establish acceptable human factors limits
  2. Cool down to 5℃ within 5 seconds - this was based on an estimate from within the team
  3. Deliver  more than 6 cooling cycles before needing recycling - generated from the average number of hot flushes a user would be expected to experience during an evening out or difficult meeting
  4. Minimise any recharging time - these are frustrating

These were carefully written not to rule in or out any specific design options, keeping as wide a door open for innovation as possible.

What are our options for technology?

There are several ways of actively cooling something down. A review of the options for our device found the following:

Thermal electric coolers

  + Quick response
  + Precision control
  + Can run in reverse to generate heating
  – Need for a large battery
  – Generates large amounts of heat and long cycle times

Stored compressed refrigerant

  + Rapid cooling
  + No electronics required → reduced cost
  + No recharge / reset time between cycles
  – Precision control challenging
  – Refrigerant release may be noisy if not managed

Endothermic chemical reaction

  + No need for electronics → reduced cost
  + Prolonged effect
  + Geometry easily adaptable
  – Slow reaction times
  – Low power density

We also rapidly dismissed conventional gas cycle and vacuum cooling as being too large, while laser cooling just isn’t at the required TRL (Technology Readiness Level). Following the above, we decided to progress compressed refrigerant.

Are we in the realm of the possible?

The next task was some basic engineering analysis to ensure that what we are aiming to do is both within the laws of physics and realistically do-able. This involved some quick sums balancing the energy of the stored refrigerant against how cold we want the device to go. The outcome was that we should be able to perform multiple cooling cycles with the volume of refrigerant which can be stored inside a smart watch.

What’s already out there?

We did some research to investigate what is already available, and identified several existing products currently on sale. These include the Menopod and Embr watch, both of which rely upon thermoelectric cooling. The Menopod cools to a claimed 5℃, but needs a large battery and even larger heat sinks. Similar in size to a computer mouse, it could not be described as wearable and takes minutes to cool down after each cycle. The Embr watch makes no claims as to ultimate temperature, instead it pulses ‘waves’ of cool to make the wearer feel cool. This reduces the battery drain and hence size while allowing it to run for longer periods before needing to cool down. Online reviews of both devices are generally positive, but some users do state they are disappointed at how quick they need recharging.

Moving into the real world

To move our theoretically possible idea into the real world I drew up a list of necessary functions and the hardware elements necessary to provide these. It started with the need to store refrigerant so that calls for a tank, and so on.

One of the benefits of working at Cambridge Consultants is the variety of experience, so I was quickly able to sit down with a group including members who have produced wireless watches, gas flow models for inhalers and temperature and pressure testing at extreme environments. The group quickly came to agreement that the biggest challenge for this product is not the tasks themselves, but getting them integrated into the small package.

Following this, we quickly investigated different options and looked at how to package the refrigerant in a segregated container, similar to a blister pack of aspirin, with each volume fueling one cycle. This removes steps from the internal workings of the device, simplifying the design and reducing costs, while maintaining the user experience.

Insight workshops

In partnership with the National Innovation Centre for Aging, based in Newcastle, we ran a series of workshops for women experiencing the menopause and hot flushes.  We focused on gathering insights about their experiences,  and we used demonstrations of ‘feels like’ prototypes to elicit feedback on ideas of how technology could help.  These were simple units which ‘faked’ the cooling effect we wanted to achieve.  We wanted to get quick feedback without investing lots of development effort.

The details of the findings of the workshop have been captured in a report and you can download this here. The response to the demo was very positive. However, the feedback was that not everyone wanted a watch - more something which could be carried in a bag or pocket.  

Alongside the workshops, we ran some testing to determine just how cold we needed to take the device and for how long. This found a range of preferences and also that temperature is not everything.  Perception of temperature changes with time as people acclimatise to a device and material is significant - think how ice cubes feel colder than their plastic trays when removing from the freezer.  

What's next?

Across this work we’ve gained lots of insight into the challenges of the menopause and ideas of how technology could potentially help. We’ve done some early investigations on one technical direction to showcase what could be possible. Likely next steps for this concept would include...

  • Industrial design of the product - how the final product should look and feel when in use
  • De-risking the main technical areas - the consumable has been identified as requiring special manufacturing processes
  • Developing the business case - we are looking at a service model where for a subscription used consumables are returned for filled ones

We’re also interested in how you could add in sensing capabilities and artificial intelligence to see if you could automatically trigger the cooling effort to combat night sweats. We have all these skills in-house and we’d love to work with you to explore this further.

If you’d like to talk to us about how we could support you with taking this, or a related lifelong health technical idea forwards then please do get in-touch!

Author
Stuart Watson
Principal Engineer

I am a chartered engineer within the Analytical Engineering group, where I get to work on a wide range of interesting projects. Prior to joining Cambridge Consultants, I spent several years engineering mechanisms for spacecraft and also have experience in mass production.