Capillary Ionic Transistor: Simple, Cost-Effective, One-Step Procedure

Technology #32918

The Capillary Ionic Transistor (CIT) nanodevice provides control of ionic transport through the nanochannel by gate voltage for use by pharmaceutical companies, medical instruments companies, hospitals, research organizations, microelectromechanical systems companies, and the chemical industry.

Nanofluidic devices such as ionic diodes and ionic transistors form key elements in ionic transport regulating systems used in biotechnological applications such as separation sensing, drug delivery, and intracellular implantation. Current ionic transistors have been fabricated using techniques such as focused ion beam (FIB) drilling, etching, lithography, and nanowire growing. Since these techniques are expensive and complex, there is a technological need for an ionic transistor that is less costly and simpler to manufacture for commercialization.


This new Capillary Ionic Transistor (CIT) employs a pulled glass capillary, combining the convenience of a conventional glass capillary with the ability to control ionic transport in different environments. This one-step procedure is easily achieved with many commercially available pullers to fabricate a micropipette into a capillary with a nanometer-sized channel. The glass used is inexpensive and provides much greater area of application, especially in biological sciences. The CIT can be used as a nanoparticles detector, biological sample sensor, atto-liter injector, medicine delivery method, ionic current controller/switch, ionic diode, ionic amplifier, or for biological sample implantation into a cell.

Technical Details

To create the CIT, a pulled micropipette filled with an electrolyte solution is immersed in a bath with the source electrode arranged inside the pipette and with the drain electrode in the bath. The voltage between the source and drain electrodes establishes a current, which is limited by pore size at the tip of the micropipette. The micropipette is coated with a conducting film, which plays the role of a gate electrode. A layer of insulating film provides an isolation of the gate electrode from the bath solution. By applying a voltage to the gate electrode, the source-drain current can be manipulated to the desired level.


  • Cost-effective
  • One-step procedure
  • Broad range of applications


  • Ionic transistors
  • Nanoparticle sensors
  • Ionic transport controllers and switches

Additional Technology Numbers: 33188