Tru: an Exploration of Micro-Interactions


The Micro Interactions that "Make" a Product

Design a concept for a control with a single input and resulting action. The control should consider visual, physical and situational cues and employ clear affordances, signifiers and feedback. A conceptual prototype should engage users in a an interaction that is useful, compelling, rich and delightful.


  • Independent conceptual design project
  • Interaction Design Studio, Spring 2015 (Instructors: Ashley Deal + Raelynn O'Leary)
  • Skills: Interaction Design, Sketching + Concept Iteration, Rapid Prototyping

project Constraints

  • The control and resulting action may be digital, physical or both.
  • Initiating the control may cause an action to happen once, multiple times or for a specified amount of time.
  • The user of the control must be able to infer its outcome from visible cues and received feedback that the action is taking (or has taken) place.

The Concept

Frustrated by the challenge of finding the perfect temperature for my coffee, I began considering how a discrete control might enable me to monitor my coffee's temperature and alert me once it's cooled to a safe drinking temperature, catching it before it gets cold. 

Starting from this personal pain point, I embarked on a deep-dive into the micro-interactions that might inform such a control. I considered a variety of options including screens buttons, dials, and sliding bars. I mapped interaction flows and feedback loops. Ultimately, I did away with buttons all together, arriving at a minimalist control utilizing gestural input and providing visual, auditory, and haptic feedback.

Tru is a small, heat sensing device that monitors your coffee to let you know when it’s the perfect temperature. Just calibrate it once, and Tru uses your fingerprint to recall your preferences upon subsequent use. Because settings are linked to a unique physical marker, Tru can accommodate several distinct users with just one device. 

The remaining inputs consider functional and situational mapping to provide for a delightful experience. Drawing upon associations with cooling down a hot beverage, blowing on the device activates calibration and measurement. Tru's reset input, shaking, calls to mind relevant functional and contextual interactions (shaking a thermometer and shaking down a packet of sugar). To make it appropriate for use in the early morning, possibly in a professional setting, Tru's feedback is clear yet subtle. The device's inset LED casts a soft diffused light, its gentle chirp is clear but not alarming, and a haptic buzz provides discreet yet reassuring feedback of recognition. Additionally, a friendly text message provides yet another gentle notification when Tru's cycle is complete.


Defining Interactions + Feedback

A significant amount of time was spent working to define the most intuitive and effective interaction flow. After several rounds of simplification, visual and auditory feedback was minimized, and a haptic response was added to denote identity recognition for regular use.


A "Functioning" Prototype

To demonstrate the experience of using Tru, I constructed a "functioning" prototype with a breadboard, single blue LED, and On/Off switch. I incorporated a gentle beeping track to serve as the final piece of auditory feedback.


Design Principles in Action

Ergonomics + Discoverability

Tru's physical form provides important cues to inform use. The organic hook-like shape affords hanging over the side of a cup, and the asymmetrical shape clearly signifies which end is to be held and which is to be inserted. The ergonomic shape of the grip also serves an important functional purpose as activation and retrieval of saved preferences are predicated upon specific handling.



The device's minimal design makes it a seamless addition to any morning ritual, be it at home or in the office. In addition to an aesthetic consideration, the principle of minimalism was applied to the device's functioning as well.  Much care was taken to simplify the number of inputs and outputs, ensuring users receive clear confirmation that an action has been initiated as well as meaningful feedback when the interaction is complete.


Functional + Contextual Mapping

Curious about the possibility of devising a solution without conventional controls, and inspired by the natural experience of gesture, I explored how movement and physicality might be injected into the experience. I examined gestural input in functionally similar interactions, referencing the action of shaking a thermometer to reset it. I also looked to the experience of drinking coffee, incorporating the ritual of blowing on a hot beverage as well as referencing the mindless habit of shaking a packet of sugar prior to emptying it into a cup of coffee.


Finally, because Tru is intended for daily use it was important to consider how interactions with the device would change over time. While the first interaction with Tru is a bit involved, once calibrated the device requires minimal effort. Piggybacking onto the instinctual practice of blowing onto a hot cup of coffee, interactions with Tru come to be an invisible part of the user's morning.

Design Process

Concept Ideation + Sketching

I spent quite a bit of time working through what the best “control” mechanism might be. I watched people buy and drink coffee. I examined the types of cups they use, the idiosyncratic rituals they follow, and the various hacks employed to cool down their coffee down. Next, I looked to a range of controls for inspiration, from radial dials, to sliding bars, up/down arrows to push buttons, trying to see which interaction mapped most naturally to ideas of temperature and the experience of sitting down to savor a cup of coffee. Though nothing really seemed to fit, this exploration was fruitful and it was this exploration that inspired me to move towards more nontraditional control inputs.

I looked to existing solutions but found that most require purchase of an expensive mug or fancy device. While I was able to draw inspiration on visual form and material, I decided to shy away from such a solution and instead focus on a control that could be used with a range of vessels and across the various locations that people enjoy coffee. This universal approach proved challenging, however, as I struggled to arrive at a solution that would work for coffee in a paper cup, a ceramic mug, and a portable thermos.

My most promising explorations included an expandable coffee sleeve with push button sides, a“smart” coaster, and some sort of insertable heat-sensing device. Ultimately, I decided to move forward with prototyping the latter option as the other solutions required that I account for the difference in temperature between the cup and the liquid inside, something that moved the concept out of the purview of a "control" and thus outside of the scope of this project.


Playing with Physical Form

From sketches, I moved onto exploring the device’s physical form, how it might fit into the fingers, how it might rest on the hand, how it might be ergonomically suited for holding and shaking. I worked through several interesting shapes and sizes, focusing on designing clear affordance into the grip. Prior to moving away from mechanical controls, I considered where a button might sit, how I could create enough leverage to push and hold it. I tested the various shapes against a range of cups. I gave them to users to see if handling was clear. The final form took into account key learnings from research, the most significant of which was that an undulating grip required users to place their finger dangerously close to the hot coffee cup. A wider, flatter grip that protrudes farther from the edge of the cup would allow for safer and more comfortable handling.