Cobalt
Cobalt is an ambulatory blood pressure monitor (ABPM) based on optoelectronic technology currently in development and user research studies. It measures hypertension, chronic conditions and arterial haemodynamics through simple skin contact. ABPMs are worn continuously for a duration of 24-48 hours to retrieve periodic blood pressure during daily activities and sleep. This technology allows Cobalt to be much smaller than ABPMs in the current market, allowing for better comfort and immersion to everyday activities
Timeline
4 months. This was submitted in 2013 for my 3rd year major project.
Problem 1
The design of the ABPM hasn’t changed since the 60s. It still currently consists of a cuff that’s wired to a monitor/recording device that can then be attached to your belt or worn as a shoulder strap. The ABPM is a highly beneficial invention which solves the issue of inaccurate results when measured as a single value since results varied between a nurse or a doctor conducting the measurement, the setting and even the time of day. However, it produced a problem of its own. Interviews of multiple past users of the ABPM as well as nurses revealed major problems with the current design. The fundamental feature of an ABPM is that it is worn during your daily activities, including sleep.
Users suffer from sleep deprivation, hindrances to everyday activities and are in constant awareness of the device.
Due to these issues, many patients ignored their physicians instructions and fiddled with the device or removed it altogether. This caused obscure readings which defeated the purpose of an ABPM.
A&D Medical TM-2440 24hr ABPM currently sold on sealmedical.com
Problem 2
Where on the body would be discreet and effective for measuring blood pressure?
Luckily a new technology at that time was in development that discreetly monitors blood pressure through laser technologies (Note that the company developing the technology had asked that their name and product not be associated with this project). This technology reduced the size from traditional blood pressure monitors to something the size of the tip of a thumb. This opened up for a smaller and cuffless designs.
Interviews with nurses and research pinpointed that areas where blood pressure monitoring is most effective are near large arteries such as the carotid artery (along neck to ear), brachial artery (arm), and radial artery (wrist). These areas are where most of my concepts revolved around.
“I would think that the best alternative...would be something that could be placed over a pulse”
Preliminary Prototypes
Rough preliminary prototypes were created to study ergonomics, form and functionality. They explored different ways in attachment to the wrist and ear.
User Testing
Testing was done in-person with participating users where they were asked to wear both prototypes for a determined length of time and perform various tasks such as sleeping, brushing their hair, carry objects etc. They were observed from a distance and notes were recorded manually and digitally. They were then asked to complete a survey of their experience.
The Results
The results showed that the prototype based at the wrist was most comfortable and so conceptual designs continued in that direction.
The Final Design
The unique 3 point locking harness, inspired by zip ties, allows for a simple pull and snap action that fits around a wide range of wrist sizes. The band around the thumb helps with stabilizing the sensor.
To avoid wearers fidgeting with the device, Cobalt does not display any data. It only provides a dim LED light that communicates whether it is measuring accurate data.
Cobalt is difficult to remove to deter wearers from removing the device. To remove, a long and thin pin is required to released the clam shell body and ultimately the device.
Interviews with nurses and doctors provided insight with how data is retrieved. Current standards involve downloading data via USB. Therefore hidden within the device is a USB to purge the data.
Final Thoughts
This project was done in 2012-2013 and since then technology and medical care has rapidly changed. At that time, wireless transmission of data wasn’t mainstream in the medical field. Now, however, wireless transmission is apparent in many modern medical devices and the smart home healthcare market is exploding. Unfortunately that means this design of the ABPM is already out-dated. And even more unfortunate, despite the rapid change as stated above, a new and more modern design of the ABPM still isn’t available. If I were to change anything with Cobalt, it would be to focus more on the home healthcare aspect and update the design that align more with current wearable tech.