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Reimagining how we monitor blood pressure

Last updated on: 20 September 2017

Striving for Seamless - The story behind EVOLV

Typical blood pressure monitors have a main unit and a cuff (armband) that are connected by a tube, these are known as “tube types”. EVOLV is revolutionary because the main unit and cuff are integrated, making it tubeless.

The Omron EVOLV Upper Arm Blood Pressure Monitor - An all-in-one, upper arm blood pressure monitor

Mr. Tsuyoshi Ogihara, from Omron Healthcare’s Design Communication Department in Japan, was the Lead Designer for EVOLV. Below he recounts how this revolution came to be.

Mr. Tsuyoshi Ogihara, Design Communication Department, Omron Healthcare

The primary concept for the design of EVOLV was “seamlessness”. We developed the product with a focus on making three factors seamless: usability, lifestyle, and management.

Seamless usability

Creating a hassle-free experience

“Fitting and operation must be hassle-free in order for users to make taking their blood pressure a habit. This was the first focus of the development.” (Mr. Ogihara)

With this goal, we wanted to remove the need for any assembly or connected parts by creating a blood pressure monitor with an integrated main unit and cuff. In order to make this happen, we first had to look into how to make each of the parts, such as the pump and sensor, smaller.

The heart of a blood pressure monitor is the valve that lets out air from the pump and the motor, and these two parts were redeveloped from scratch. However, it wasn’t simply a matter of making them more compact.

“There are limits to the extent things can be made smaller. If you make a motor more compact, it makes a higher frequency sound when in operation, and this can be loud for the users. So, simply making the parts smaller was not enough. The motor was quite loud in earlier models, but we were successful at controlling it with software to make it as quiet as possible, even with the same size of motor.” (Mr. Ogihara)

Balance with usability was also essential. “We worked with the development team to investigate a variety of structures with the aim of achieving both compactness and ease of use. Making something too small conversely makes it more difficult to use. Sometimes the opinions were divided within the team, but we discussed each issue and came to decisions by studying the balance between usability and wearability of around ten different layout patterns for the main unit.” (Mr. Ogihara)

Making the main unit smaller and thinner is essential for integrating the main unit and cuff. In the initial stage, a full-scale mock-up was made with styrofoam to investigate the balance between wearability and usability.

Various parts are housed in the main unit, such as the pump, motor, and sensor. Weight and centre of gravity were also verified, as they directly affect wearability and usability.

Ensuring optimum wearability

EVOLV was developed in order to resolve the hassle of wearing a conventional blood pressure monitor. However, the advantage of a conventional blood pressure monitor is that measurement results are easy to read because they are usually displayed on a large, independent screen. This presented challenges when trying to integrate EVOLV’s initial display with the main unit and cuff.

In light of this, an organic electroluminescent (EL) display was employed instead. EL has a higher resolution than conventional liquid crystal and it has superior visibility without the text on the display becoming muddled.

Much like with the motor sound, improving wearability was not simply a matter of making the device smaller. It was necessary to consider the positioning and layout as well, particularly from the perspective of ensuring that the ease of viewing the display was not sacrificed.

“Since the display is embedded in the cuff, we first had to think about the direction in which it would be worn. When we carried out actual usability tests, we learned that there were many users who found it better to have the control surface facing their way.” (Mr. Ogihara)

However, this wasn’t the only issue.

The issues of visibility that were sacrificed by making the display smaller were overcome by using an organic EL crystal display. It is high resolution, so even small text can be displayed without becoming muddled, and it can also allow for a wider variety of messages to be displayed such as symbols and emoji.

“Blood pressure monitors are always calibrated before each measurement. Conventional liquid crystal displays take 4 to 5 seconds to calibrate, but it was barely noticeable since it happened in tandem with the start-up of the screen. However, the calibration feels very long with organic EL, which doesn’t have a single power-on action. We were able to shorten the calibration time by about 1.5 seconds using software. It’s surprisingly difficult to find the right amount of time that’s neither too long nor too short.” (Mr. Ogihara)

Between performance and convenience

One major point of “seamlessness” was making accurate measurement possible, regardless of the direction or position of the cuff. According to Mr. Ogihara, authorisation and legal barriers from various agencies posed bigger problems than technological challenges.

“A blood pressure monitor, which is sold as a ’medical device,’ must meet national agency standards, such as those of the Ministry of Health, Labour, and Welfare, in order to be authorised for sale. We put a lot of effort into verifying that blood pressure could be measured properly no matter how the cuff is positioned around the upper arm. We have finally reached the point of releasing it as a product, but the concept for the device had existed for about 10 years, and the project took about 3 years.” (Mr. Ogihara)

The cuff’s internal air pouch is about 1.5 times the length of conventional devices. Another layer of fabric was added to improve both air tightness and comfort.

The feel of the cuff against bare skin was also important. The basic structure contains a sensor that detects blood pressure inside the cuff, and it is entirely surrounded by an air pouch. However, the structure of EVOLV, which allows the cuff to be worn in any position or direction, has an air pouch that is 1.5 times longer than in conventional devices.

The air pouch must be kept airtight, and although it is easier to maintain performance by surrounding it with fabric, the fabric must be coated to keep air from leaking through it, which can result in a bulky feel that stands in the way of user comfort when worn.

“We started by working with the lead developer to select the materials. Ultimately, we solved this by adding another layer of specially chosen fabric to the one that would be in direct contact with the user’s skin.” (Mr. Ogihara)

Seamless in daily life

Achieving a “self-standing” blood pressure monitor

The second concept the product aimed for was seamlessness in daily life. According to Mr. Ogihara, the biggest disadvantage of conventional tube-type blood pressure monitors for Omron Healthcare was their appearance.

“We felt it was necessary for the device to stand up on its own to further eliminate aspects that users might find troublesome. Since it’s tubeless, we wanted something that wouldn’t get in the way even when it’s sitting on a table, and can be used right away whenever you want to measure your blood pressure. We asked the development team to make sure it could stand up on its own.

It was essential for the main unit to be able to stand up on its own in order to improve everyday usability.

Several prototypes were created with a 3D printer in order to ensure that the main unit could stand on its own with all of the parts inside it while maintaining the optimal cuff width when worn. The positions of the display and operating buttons were also reviewed at the same time.

However, the reality was that it wasn’t so easy to get the device to stand up. The easiest way to make it stand up was to make the cuff wider, but since it is a product that is widely sold overseas as well, it was necessary that the width of the cuff be compatible with a relatively wide range of users. It also needed to contain a mechanism for controlling the air pouch. Because of this, several mock-ups of the main unit were made with a 3D printer, and the investigation continued.

“The main unit is slightly curved on its interior side since it was intended to be worn on the arm. The cut-out surface appears flat at first glance, but it is actually slightly twisted. If it were straight, it would get stuck in the mould since the unit is curved.” (Mr. Ogihara)

Seamless in management

Creating an intuitive digital experience

The third layer of seamlessness in the design concept relates to management. In addition to displaying measurement results on the main unit’s display, EVOLV can also be connected to a smartphone via Bluetooth to check and manage data through a dedicated app, ‘OMRON connect’. The designers remained conscious of maintaining a connection process that could be easily guided through the app to eliminate any difficulties related to smartphone connection.

The ‘OMRON connect’ app’s screen. Making the navigation and process of connecting EVOLV to a smartphone simple and easy to understand.

Going for zero

EVOLV was born out of the desire to improve usability and make it possible for people to measure their blood pressure habitually without hassle. As Mr Ogihara demonstrates, EVOLV’s design went above and beyond simply integrating the main unit and cuff, the product is packed with other user-conscious features and considerations that are otherwise hard to notice at first glance.