UX Design: Motion Sensor Sink

Final Deliverables

Team Size + Role

Time Frame

Programs Used


Concept for a re-designed public restroom sink motion sensor including physical prototypes, user interface applications, and contextual mock-ups

1 / Interaction designer

2 weeks (Winter 2019)

Adobe After Effects/Illustrator/Photoshop/Indesign, Solidworks, Keyshot

Carnegie Mellon University

Motion Sensor Template.png

The Horrors of a Public Bathroom

Vastly different from a home bathroom, the general perception is that a public bathroom is dirty, gross, and a place best used as quickly as possible while touching as little as possible.


Taking a more systematic approach to charting out the various interactions was the best way to manage them and analyze how they contribute to the balance of cleanliness and ease of use in public bathrooms. 

Motion Sensor Redesign Process Documenta

Research + Interaction Inventory

Through exploring various public bathrooms and taking visual notes, five universal interactions were defined: locking a stall, flushing, washing hands, and two methods of drying hands. For each one, various factors were looked at and recorded, usually by focusing in on one particular control for each interaction. 


Because of my own personal experience, along with insights from peers and students, I decided to start running with the interaction of washing one’s hands with the control of an infrared motion sensor, since there seems to be a lot of (justifiable) hatred towards that specific public bathroom interaction.

Motion Sensor Redesign Process Documenta
Motion Sensor Redesign Process Documenta

Ideate + Prototype

Since a lot of public bathroom controls have transitioned to using motion sensors, observing how those handle signifiers and feedback helped shed light on the control. This led to observing hand dryers, paper towel dispensers, and automatic flushers. 


Three problems with current motion sensors in sinks were noticed:


1. Sensors are hard to spot, and thus ambiguous about their field of detection

2. Space of interaction does not map to traditional faucet controls

3. Little to no feedback

From there, ideas were generated by only focusing on two variables:


1. Shape/size of sensor housing

2. Orientation and placement relative to the sink

Motion Sensor Redesign Process Documenta

Form: Sketches that explore forms with clear signifiers via shape of sensor housing and orientation relative to the rest of the sink

Final Solution Logic

Taking those two variables, the following goals for the redesign were:


1. Make the sensors easy to discover

2. Map motion controls to traditional sink faucets


From there, two characteristics of a solution are very apparent: Make the sensors a more prominent, larger feature of the sink instead of hiding them away, and map to traditional faucets. 


The faucets are the first thing people notice of any sink, as it tells them whether the sink is a traditional one or an automatic. Having two sensors located adjacent to the faucet head not only makes the sensors easy to discover, but also plays off of the perception that the interaction space for turning on a sink is behind the faucet head, which is always true for traditional sinks with faucets. Making the sensors visible also opens the door to information display, which became an aspect of the redesign.

The sensors are sloped upward to reduce water build-up; puddles would form as wet hands drip water on flat, horizontal sensors. The slope upward also discourages people from placing drinks and cups on the sensors.

Motion Sensor Redesign Process Documenta