A transcutaneous controlled magnetic microvalve based on iron-powder filled PDMS for implantable drug delivery systems

This paper reports a magnetic microvalve based on iron-powder filled polydimethysiloxane (PDMS) for implantable drug delivery systems, which allows transcutaneous control when implanted under the skin. It does not require any implanted power source or receiver including batteries, RF coils, piezoelectric materials, etc. Only a magnet is required to open the microvalve for drug delivery. A pressurized balloon reservoir is used to pump the drug when the microvalve is open. This simplifies the structure design and reduces components for implanted devices. Only a single mask is required to define the silicon cavity for valve plug and legs with different width and depth when anisotropic etching with potassium hydroxide (KOH) is used. The defined silicon cavity was then filled with PDMS that has been mixed with iron-powder to form the body of valve plug and legs. After removing the excess material by a blade, the magnetic microvalve is finished. The microvalve was packaged with transparent acrylic for making valve channels for testing with a permanent magnet to open the valve by magnetic force.