Research highlights

Bioactuator:Vorticella actuation in microfluidic systems

Vorticella is a microorganism with a stalk capable of linear actuation with a 100 µm working distance. Contraction and extension of the stalk are induced by Ca²⁺ (calcium ions) and chelators such as EDTA and EGTA. As the stalk does not require an external power source for actuation, it has intriguing possibilities for applications in microfluidic systems.

However, controlling Vorticella actuation in a microfluidic device remains a major challenge for these applications. Now Moeto Nagai and colleagues in Japan and Usa at Toyohashi University of Technology have demonstrated that pneumatically controlled microvalves can be used as a control system for the actuation of the stalk.

The experiments were conducted in three steps: microfluidic devices were fabricated by multi-layer soft lithography; the Vorticella were introduced and cultured in the device; Ca²⁺ and EGTA solution were injected.

The length of the stalks changed between 20 and 60 μm in the presence of Ca²⁺ and EGTA, resulting in a working distance of about 40 μm.

The stalks of Vorticella show genuine potential for applications in microsystems such as micro-positioners and microvalves.

Reference:

Moeto Nagai^1,2,Sangjin Ryu³,Todd Thorsen³,Paul Matsudaira³ and Hiroyuki Fujita²

Chemical control of Vorticella bioactuator using microfluidics

Lab Chip, 10, 1574–1578 (2010).

Digital Object Identifier (DOI): 10.1039/C003427D

¹Moeto Nagai is now at Department of Mechanical Engineering, Toyohashi University of Technology

²Institute of Industrial Science, The University of Tokyo

³Massachusetts Institute of Technology.