Letters to Nature

Nature 397, 335-338 (28 January 1999) | doi:10.1038/16898; Received 25 August 1998; Accepted 16 November 1998

A controlled-release microchip

John T. Santini, Jr1, Michael J. Cima2 & Robert Langer1

  1. Department of Chemical Engineering, and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
  2. Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

Correspondence to: Robert Langer1 Correspondence and requests for materials should be addressed to R.L. (e-mail: Email: rlanger@mit.edu).

Much previous work in methods of achieving complex drug-release patterns has focused on pulsatile release from polymeric materials in response to specific stimuli1, such as electric2, 3, 4, 5 or magnetic6,7 fields, exposure to ultrasound7, 8, light9 or enzymes10, and changes in pH11 or temperature12, 13, 14. An alternative method for achieving pulsatile release involves using microfabrication technology to develop active devices that incorporate micrometre-scale pumps, valves and flow channels to deliver liquid solutions15, 16. Here we report a solid-state silicon microchip that can provide controlled release of single or multiple chemical substances on demand. The release mechanism is based on the electrochemical dissolution of thin anode membranes covering microreservoirs filled with chemicals in solid, liquid or gel form. We have conducted proof-of-principle release studies with a prototype microchip using gold and saline solution as a model electrode material and release medium, and we have demonstrated controlled, pulsatile release of chemical substances with this device.