Graduation assignment | 3D printing of microfluidics: electrostatic valves

About us

TNO at Holst Centre pioneers printed electronics with an extensive portfolio of breakthrough technologies. One of the most promising innovations of the past years is 3D printed electronics. This technology boosts the performance of next-generation electronic devices like sensors and medical instruments where volumetric constraints apply. It combines structural and electronic manufacturing in a single step. This means there is no longer a need for separate circuit boards or electronics layers, giving complete three-dimensional design freedom and inherent protection from dust and dirt. This patented printing process is scalable up to 10,000 cm3 of integrated electronics per hour, making it significantly faster than inkjet and dispensing technologies. At this high-speed, resolutions of less than 10 microns can be realized, opening up the possibility to embed bare dies and ultimately enabling serial manufacturing of systems-in-package.

Minimum project duration is 6 months, starting as soon as possible. A more detailed plan will be drafted together with your academic supervisor.

About this position

Microfluidics is a rapidly advancing technology that allows precise manipulation of small fluid volumes. While many functional components have been successfully miniaturized and integrated into microfluidic chips, the control of fluid flow often still relies on external valves and pumps. Unfortunately, these peripheral instruments tend to be bulky, and result in significant dead volumes during operation. Moreover, they cannot be efficiently produced in large quantities. Consequently, there is a pressing need for more integrated solutions to meet the growing demand for complex workflows that involve multiplexing and parallelization.

Microvalve integration is particularly crucial for enabling fully integrated microfluidic systems. An electric valve that does not require moving parts and is relatively easy to manufacture is the electrostatic capillary valve. It utilizes the manipulation of surface interaction properties of the fluid with the channel walls as a working principle. The manipulation of surface interaction properties can be achieved by applying a voltage over the liquid-air interface.

What we expect from you

In this graduation project you will develop a 3D printed electrostatic valve. Your tasks will be:

  • Literature study: Study the principles of microfluidics and the significance of electrostatic microvalves.

  • Design: Using computer-aided design (CAD) software (such as SolidWorks, Fusion 360, or Tinkercad), create a 3D model of your microfluidic valve.

  • Prototyping: Use layout editor software (such as Clewin or Klayout) to make a design for prototyping; select appropriate printing parameters and print a prototype of your microfluidic valve using Holst Centre’s proprietary 3D printer.

  • Testing and Optimization: Assemble your printed valve into a microfluidic chip or system. Test its functionality by introducing fluids (e.g., water, colored solutions) and observing flow control.

  • Optimize the design if necessary (e.g., reduce burst voltage, enhance actuation efficiency).

  • Write final report.

You are an ambitious hands-on student from mechanical engineering, materials science or (applied) physics. You have good communication skills in English and you are independent, but also a team player. This student projects will be an internship with a preferable total duration of 9 months (with the least period of 6 months). If you are looking forward to work in a challenging atmosphere with highly skilled co-workers, then please apply for this vacancy now.

What you'll get in return

You want to work on the precursor of your career; a work placement gives you an opportunity to take a good look at your prospective future employer. TNO’s Holst Centre goes a step further. It’s not just looking that interests us; you and your knowledge are essential to our innovation. That’s why we attach a great deal of value to your personal and professional development. You will, of course, be properly supervised during your work placement and be given the scope for you to get the best out of yourself. Naturally, we provide suitable work placement compensation.

TNO as an employer

TNO is an independent research organisation whose expertise and research make an important contribution to the competitiveness of companies and organisations, to the economy and to the quality of society as a whole. Innovation with purpose is what TNO stands for. With 3000 people we develop knowledge not for its own sake but for practical application. To create new products that make life more pleasant and valuable and help companies innovate. To find creative answers to the questions posed by society. We work for a variety of customers: governments, companies, service providers and non-governmental organisations. Working together on new knowledge, better products and clear recommendations for policy and processes. In everything we do, impact is the key. Our product and process innovations and recommendations are only worth something if our customers can use them to boost their competitiveness. We are an international team with diverse cultural background. We embrace everyone with respect, open mind and warm heart.

Has this job opening sparked your interest?

Then we’d like to hear from you! Please contact or for more information about the job or the selection process.