presSURE: a study of microinteractions


This project was created as an exploration of microinteractions for an Interaction Design Studio course. The goal of the project was deconstruct and then redesign an existing microinteraction using the principles of good interaction design from Alan Cooper, Dieter Rams, Don Normam, and Dan Saffer.

  • Design prompt: Using the context of a car, design a control for a microinteraction that uses visual, physical, and situational cues and leverages well designed affordances, signifiers and feedback. Develop a control concept that is intuitive and delightful to use, and create a digital or physical prototype that demonstrates the device’s interactions. 
  • Team: Individual design project
  • Tools & techniques used used:  Rapid prototyping (cardboard, play dough, Instamorph plastic, laser cutter), interaction design, ideation, sketching
  • Produced for: Interaction Design Fundamentals Studio, Carnegie Mellon School of Design
  • Project length: 3 weeks, Jan - Feb 2017


The concept

Have you ever tried to check the pressure of your car tires? It is not an easy or straightforward process, and because of this, many drivers neglect to monitor their tire pressure.

presSURE is a smart tire pressure sensor that is designed to make monitoring your tire pressure simple, intuitive, and painless. The presSURE sensor is integrated into your tire’s nozzle cap. Its low profile design seamlessly blends in with your hub cap system without impacting your car’s style.

presSURE is preprogrammed with a car’s recommended tire pressure and is activated as soon as it is screwed onto the wheel. Using color coded LED indicator lights that illuminate on the wheel, the device enables a driver to know their tire pressure at a glance.

When the tire pressure is low, a red LED automatically illuminates on the wheel, contextualizing the device’s feedback in the exact place where action is required from the user, accompanied by a friendly text notification.

Drivers can also check their tire pressure at any time by pressing the top of the device, and the LED indicator lights will illuminate with a simple red/green color status. For those that want more detailed information, a text message is sent with the exact pressure reading. Sophisticated users can also set a custom tire pressure setting by removing the device from the wheel and twisting the top cylinder, which will then illuminate blue and initiate a text exchange to confirm a new pressure setting.

When the device is back on the wheel and tire pressure is appropriate, presSURE politely fades into the background.

Design Principles


presSURE’s form was driven by three primary factors: intuitive physical affordances, universal graspability, and seamless integration into the hub cap system. The base of the device is square, with gentle grooves for your fingers, allowing a user to easily grasp the device and screw it onto the nozzle. The top of the device is cylindrical, inviting a user to press it (to check tire pressure) or twist it (to customize the pressure setting). The composite form is low profile, so as not to stick out from the wheel and to mimic the look & feel of a hub cap’s bolts.


Acknowledging that drivers don’t want to be bombarded with notifications and unnecessary information, presSURE’s feedback is predominantly visual, but intentionally unobtrusive. The primary feedback mechanism, LED lights that illuminate the wheel, use a straightforward green/red status color system, just like a stoplight, which is conceptually appropriate for the setting. Feedback is consistent in every interaction. A solid light indicates status, and a blinking light indicates a text being transmitted between the device and a user’s phone. 



Special consideration was made to determine when it was appropriate for a driver to have general information (Tire pressure is “good”) versus detailed information (Tire pressure is exactly 33 PSI). Recognizing that most drivers are satisfied with the general information about their tire pressure (and may not even be familiar with tire pressure units), efforts were made to minimize inputs required from the user and feedback mechanisms from the device to be as simple as possible for the basic user. However, mechanisms are built in for a sophisticated user to access more detailed information from the device upon request. Simplicity is the default, and details can be invited by the user.

Context & mapping

Dashboard notifications can often be confusing because they are divorced from their context. Situating the device directly in the place where action is required allows for direct mapping of the feedback and function. By having the feedback contextualized, the device helps educate the user on the dynamics of the tire pressure system, instead of obscuring it; technology that adds to our awareness, instead of detracting from it.  

Interaction Flow

A significant amount of time was spent refining the interaction flow so that it was consistent and intuitive across various use cases. For the first use, the amount of user input required to activate the device was minimized as much as possible. On subsequent uses, a user can ask the system for additional feedback or to adjust preferences, but in its defauly state, presSURE politely stays in the background. When tire pressure becomes low, the device proactively notifies the user with a text and visual signal on the effected tire. 

Design Process

Early ideation

The exercise started with an interaction inventory of the entire car to better understand the universe of microinterations within the domain. I focused on manual interactions because I was particularly interested in exploring a solution that was physical, rather than digital. I quickly identified a number of pain points with existing tire pressure gauges, including unclear feedback, confusing physical affordances, and unsatisfying ergonomics. 

I was particularly interesting in exploring a device idea that was more ergonomic and easy to handle, particularly for people mobility or grip issues. I wanted to explore ways to communicate to a user when the seal of the gauge and corresponding pressure reading were correct. I started with looking at gauges that were separate from the tire, but then started wondering if you could create a gauge or sensor that was integrated into the tire, negating the need for a separate device.

Side note: I acknowledge that some newer vehicles have automatic tire pressure sensors integrated into the mechanics and dashboard screens. However, I wanted to explore the physical side of the interaction and address the needs of older or cheaper cars that do not have integrated sensors for the purposes of this project.


Exploratory prototypes

I decided to quickly prototype two different concepts, one handheld device and one integrated with the tire cap. I was curious to understand the interaction possibilities that each afforded and what body movements would be required to use with each type of device. I pride myself on being scrappy and making use of what is available, so I constructed my quick prototypes out of materials found (or scavenged) from the school building. 


Refining the prototype

I liked the simplicity of the cap integrated prototype, and decided to proceed in that direction with another iteration of more refined prototypes. In this round, I took a closer look at form and what  input mechanisms could be possible on the device and where on the device the feedback could be displayed. I initially explored having the precise tire pressure reading shown on the device, but after an exercise of trying to simplify the functionality as much as possible, came to realize that the pressure reading may not be necessary for most users. 

I ultimately settled on the cylindrical shape on a square base, as it seemed like the most elegant and minimalist design that still achieved its function, and created a working prototype with an LED light and simple circuit. The material I was using to prototype, InstaMorph, limited my ability to adjust the scale of the form, so I decided to move to acrylic and use the laser cutter to cut out layers of the form arriving at my  final prototype for this project. If I had more time (skills and resources), I would like to experiment with 3D printing the form and find ways to improve the ergonomics of the base of the device to improve graspability.


Working Prototype

After experimenting with a number of materials and moldable plastics, I created a functioning prototype using laser cut acrylic. Inside the form, I wired a simple circuit to a multicolored LED, and mounted it to a mock-up of a tire, also laser cut, in order to demonstrate the interaction flows in class. The prototype was also functional enough to be installed on a car for testing out the interaction flow.