Aquasist - Monitoring hydration in athletes

This 5 month project was part of the Sport Innovation Minor at TU Delft, and was in collaboration with 3 students studying Mechanical Engineering, Human Movement Sciences and Product Design Engineering.

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Develop an intelligent measuring system which can measure the fluid loss of the body and monitor the uptake of liquid in a bottle.

The data should be stored in a database and feedback given to the user through a smart- phone App and a bottle.



During sports, participants lose fluid, minerals and energy. All of these components are necessary for the metabolism of the human body and need to be restored. Howevermost people have little idea how much they need to drink to restore the correct level, and often drink less than actually needed. This is dangerous because it can lead to discomfort and decreased performance, or in worse cases even to unconsciousness, strokes or death. Over-hydration is also dangerous. High sodium differentiation in body cells can cause swellings. In this project, the emphasis is put on enabling athletes to drink the needed amount of water, before, during and after the sport.


Key questions

“How can people easily monitor their fluid loss and required fluid uptake during sports?”

“How can hydration status be assessed?”

“How can information about hydration status be provided to an athlete?” 


Initial research areas

Various surveys were conducted with committed  sports enthusiast to gain an understanding of the awareness of issues with incorrect hydration, how they currently stay hydrated and their willingness to change how they do this.

Survey results

Survey results

Over 100 people took part in the survey, and these were the key findings:

- Only 30% of athletes monitor their hydration level

- 60% of athletes think monitoring hydration is useless

-  The majority of athletes only drink when they are thirsty

- Over 60% would be interested in a monitoring system

- From these people 90% would want it integrated into their smartphone.


Literature research findings

Monitoring hydration during sport is a very common subject and therefore there is a lot of material available on this topic. After looking through many reports and papers 3 key things were discovered.

- When someone becomes thirsty they are already dehydrated to a point which creates sporting disadvantage

- The best way to monitor hydration level is by the colour of urine

- Being correctly hydrated increases performance a noticeable amount


Observational research

At the ADO Den Haag training grounds

At the ADO Den Haag training grounds

As the produce is targeted towards professional and semi-professional athletes many visits and interviews were done with these people. We worked directly with a professional football team (ADO Den Haag) where we worked directly with the coach and physiotherapist alongside talking to the players themselves. Visits were also made to other professional teams including the Dutch basketball team amongst others.

The design team observing training

The design team observing training

Looking at how the current fitness monitoring worked

Looking at how the current fitness monitoring worked

Talking directly with the head coach

Talking directly with the head coach

Observing professional basketball players

Observing professional basketball players


Project focus

Based upon findings from talking with amateur athletes and many interviews with professionals it became clear that there would be 3 key components to the solution, all working flawlessly together.

Water bottle

- Track the amount of water consumed by the athlete.

- Give visual feedback on the amount of water that should be consumed.

- Hold enough water for a typical work out period.

Smartphone app

- Work in conjunction with the water bottle.

- Track athletes movements.

- Record urine colour.

Data System

- Determine the amount of fluid that should be consumed by estimating the athletes current level of hydration.

- Learning system that develops an understanding of how much fluid the athlete looses during a giving period.


System Design

The first focus of the project was to design the full data system in which all the other components would be based around. Below was the initial rough layout of how this would work.

There are 3 core components: The bottle which communicates with the smartphone through bluetooth. The smartphone which is the core of the system, storing data locally and in the global cloud. And the learning data base itself.

This system was shown to the sporting professionals we had worked with earlier in the project and at the point a full data system was drawn out. This is extremely complex to ensure it works effectively and the head coach and physiotherapist at ADO Deg Haag said it was the most comprehensive and effective system they have ever seen. This system can be seen below.


Bottle development

To begin the development of the bottle the internal components were considered. This area of the project was worked on mainly by the Mechanical Engineer, analysing the most appropriate ways to monitor the level of fluid passing through a tube. It was decided that a rotational flow meter (impeller) would be used with an embedded magnet to allow a sensor to determine when it was rotating. Based on this it is possible to determine how much liquid is being consumed every second the impeller is moving.


To test the design of the impeller 3D printed models were made and tested using slow motion video equipment.


Bottle design

After the core internal components had beed designed and tested, form studies began regarding the overall design and appearance of the bottle. The first stages were in researching anthropometric data using the DINED system, this allowed us to create a bottle with a diameter the majority of people in the EU could use.


Following on from this, materials were decided based upon research and existing products and then simple form studies began. Taking into account the target market and the associated product language of sporting goods a recognisable visual style was created. Quick concept sketches and full renders were used to communicate these ideas.

Initial concept sketches

Initial concept sketches


At this stage the it became clear that the focus of the design should be on the visual feedback system of the bottle. Through many iterations and testing it was decided to use a rod in the centre of the bottle to indicate the level to drink to through LED's. This was the most simple option as it meant the entirety of the electronics could be stored in the lid keeping the actual design of the bottle very simple.

Additional research was done into the correct materials, the bite valve system, adapting the design for manufacture, reducing the cost of production and creating a basic overview to how the electronics would work.


Key features


All components are joined to the lid allowing the bottle to be cleaned easily.


LED's embedded in tube indicating the level to drink down to.

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Replaceable silicone bite valve.


Single part housing for all electronics.


Standard bike cage bottle rack width, with ergonomic grip.


Manufactured from PET to provide high impact resistance when dropped.

Induction charging port to allow all electronics to be kept in a fully enclosed part.


Single button, for on/off and to reset measurements when bottle is refilled.


Electronics will be stored in the left compartment.


Impeller located in through pipe which will rotate when water is consumed.


The impeller has a single magnetised blade allowing a sensor to pick up when it is rotating over a et speed.


Logo design

A logo was developed to mirror the simple design of the product and create a strong visual brand heavily associated with sport. Quick sketching techniques were again used before mocking up the design in illustrator and then developing the final design that mimicked the bottles lid. This process can be seen below.


App design

The design of the app was a crucial part for the project as it is the main source of user interaction with the product. Because of this extensive research was done into UI theory and many iterations were created before settling on the final interface.

Initial app system user flowchart

Initial app system user flowchart

Once the design and functions of the app had been decided vast numbers of sketches and quick mock ups were created to test the usability of the interface, and to discover if any key aspects had been missed.


An animation of the final app can be seen below. The core functions were to inform the user of their current hydration status whilst mirroring the feedback given on the bottle and recording standard tracking data.


Final proposal

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