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Hydrogel Micro Valves

Our patented microvalve has no membranes and is therefore extremely reliable and robust. It works because the polymer particles captured in a small cage dramatically change their size (by more than a factor of 10!) with temperature. Our standard valves feature a biocompatible switching temperature of 34 °C.

If you work with aqueous solutions, you will hardly find a valve that can be more easily incorporated into microfluidic networks. It is also an indispensable accessory for our microfluidic platform MicCell .

Schematic View Fluid Channel with Hydrogel
Hydrogel particle actuator in standard 1/16" fitting for low dead-volume operation. Left: manual sample injection into a micro-funnel (red), right: automatic sample injection through a PEEK capillary (inner diameter 25 - 762 µm).
 Scanning electron micrograph of a photopolymerized hydrogel as the smallest version of the microvalve. It is seen as small bulge between two dark channel walls and above a heater (light color).
   

Features

  • Various housings available. Death volume of the whole device approximately 5 micro liters.
  • Hydrogel actuator is formed by polymer particles, captured in a micro-basket of (800 x 800 x 200) µm³.
  • Dependent on the temperature, the polymer is shrinking or swelling.
  • Phase transition temperature TT is adjustable. In the hydro gel used in GeSiM valves TT = 33.8°C.
  • To improve dynamics, the working temperature of actuator is adjusted to 28°C.
  • Normally closed hydrogel valves are available.
  • Heating power to actuate the valve is in maximum 250 mW, the applied voltage is between 3.5 V and 5 V.
  • Switching time to close and to open the valve is about 1 sec.
  • Pressure tolerance is given up to inlet pressure of < 5 bar.
  • Control unit to handle the valves in complex networks is fully software driven.
 

Valve Characteristics

Performance of the hydrogel valve under normal operating conditions (250 mW).


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