Silicone as input and output interface

TUMI (pronounced as Tummy) is a soft-robotics project exploring the potential of inflatable translucent silicon as an input and output interface.

It is an interactive night lamp that uses tangible, visual, and auditory stimulation to help children sleep. Its belly continually inflates and deflates to mimick the breath of a pet pig. To signal children for bedtime, it starts yawning and flashes pink light. When the children put it to sleep by repeatedly stroking its belly, it snores with slower breath and pulsates gentler shades of blue light.


We adopted a bottom-up design process by first brainstorming the unique properties of soft robots and their potential usage. We identified three areas that we would like to experiment with - color diffusion as well as simultaneous input and output interface. We also discussed our personal expectations of the project and decided to explore soft robotics in a commercial context.


With the above ideas in mind, we researched further into the potential use cases and created a mood board to capture our inspiration and product narration. We found that the inflation and deflation of silicone bladders mimick the breathing motion of fluffy animals nicely. And cartoon characters like Snorlax and Totoro further inspired us to build a product that helps kids maintain a healthy sleeping habit.


A prototype embedded with functioning electronics and fabricated with silicone casting and 3D printing.

Pneumatics Design

We designed a four-way junction connecting the pneumatic components. In the inflation phase, the air pump injects air faster than the escape can let out, guiding the trapped air to the silicone bladder and slowly increasing the sensor reading. In the deflation phase, the air pump stops and the air is gradually released into the environment through the escape and the pressure decreases. When user squeezes the bladder, the sudden pressure change creates a spike in the sensor reading that is much higher than that during the inflation phase, enabling us to detect user input.

An LED array is put directly under the translucent bladder so that the light could diffuse through the silicone organically.


We used 3D printing to create both the mold and the prototype itself. The models were designed using SolidWorks. The size of the body was designed in a way that all electronic parts could fit nicely. After testing the integration and interfaces among different components, we colored the body with a matte pink spray paint.


User Manual

A booklet listing the internal parts, safety precautions and detailed instructions for parents and kids.