EOP Soft Interfaces

Embedding sensing and actuation in one thin soft material

Presented at Robosoft 2025

EOP soft Interfaces

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Tags

EOPs Silicone Flex PCB

Date

July 2025 (4 months thesis)

Links

Using electroosmotic pumps (EOPs), these soft interfaces enable silent, high-resolution shape change in thin formats. The interfaces can sense and respond, offering subtle gestures that express presence, intent, or a state. Rather than replicating conventional controls, they invite new forms of interaction.

Interaction

This thesis began with a vision of soft shape-changing interfaces, developed over the past two years and shared through the platform softinterfaces.com. It explores how technology can be expressed through form and integrated into the materials that shape our surroundings. Through experiments with magnetics, textiles, fluidics and pneumatics, I investigated ways for interfaces to communicate not only through sight and sound but through motion, deformation and touch. Reciprocity is the core of soft interaction; sensing and actuation must be designed as one, so the interface can feel and move in a single continuous conversation. In doing so, I became aware of how material dictates experience. The stickiness of silicone, the noise of air, and the bulk of tubing aren’t just technical frictions they influence how people engage with the interfaces, what they expect from it, and how it fits into everyday life.

Vision on interaction design

Design Process
Why do we want our interfaces to be soft?
Why EOPs?
Design Process
As previous soft interfaces made (e.g. VENTI, Wool Steel Wool) needed bulky electronics, got hot, and made noise. The electro osmotic effect was chosen to explore

With the earlier soft interfaces I kept running into the same limitations: noise, rigidity, leakage, bulk and heavy power consumption. They were difficult to miniaturise, impractical to embed and still fell short of the subtle softness and interaction I envisioned. Creating thin, silent and high resolution actuation that disappears into surfaces demanded a different approach, which led me to electroosmotic pumps (EOPs), a scalable fluidic technology with no moving parts that supports both actuation and embedded sensing.

Expressivity
Design Process
Exploring the expressive interactions you could make using EOPs

Method

Rather than outsource the technical development or rely on speculative prototypes, I chose to build these pumps myself. As a designer, I believe knowledge comes through making, not just imagining how something could work, but physically engaging with materials, circuits, and failures. Throughout this process, I interviewed experts from BMW, Disney Research, Accenture, and research groups to position EOPs within a wider design and industry context. Rather than validating a novel actuator, this thesis explores how designers can actively shape its expression and use. It demonstrates how designers can engage directly with emerging technologies through physical prototyping, positioning design as a bridge between early-stage technological development and applied contexts in sectors such as soft robotics, automotive and entertainment.

Design Process
Exploring the expressive interactions you could make using EOPs
Making logs (see all here)
Design Process
Logging the creation of my first custom PCB ever
Design Process
Annotating material properties and recipies
Design Process
First high voltage control circuit
Design Process
Python script to create the electrodes as I found out that the shapes I wanted were not possible to create manually
Design Process
Import an SVG shape and automatically vias are placed with the correct NETs. Also allowed me to easily update the pitch and hole sizes to fit to the manufacturer constraints
Design Process
Final electrode shapes
Design Process
Abstract fluid shapes on the electrode
Design Process
Figuring out the high voltage control chip (HV507) as there is almost no documentation on high voltage chips
Design Process
Assembly of a pump
Design Process
Found unconnected ground and figured out the wiring
Design Process
Clock and latch times need to match precisely, a logic analyser was used to time these

Expert Interviews

Design Process
Interviewed seven companies or research groups about their view on electro osmotic pumps and its interaction design. Above some of the applications mentioned during these conversations are visualized
Design Process
Overview of all possible applications mentioned
Design Process
Quotes
Design Process
Quotes
Design Process
Deflated EOP
Design Process
Inflated

Sensing

Design Process
The pump electrodes can also be used as pressure sensors when glueing Velostat in between
Motion Pattern 3
The sensor allows for pressure sensing and multi touch
Motion Pattern 3
The sensor values visualized, sensor still works well through the EOPs as they are so thin and fully soft.

Final controls

Design Process
The custom HV controller can control 32 electrodes meaning it can control 16 pumps up and down using voltages around 100Volts and pulling 2mA. The booster is used to convert 12Volts to a high voltage. The custom HV board also includes simple voltage dividers to read out the sensors
Using the control board to actuate the pumps one by one
Next Project: VENTI  →