Secure wireless actuation of an implanted microvalve for drug delivery applications

Abstract

The capability to wirelessly control fluid flow through a microvalve can emerge as anattractive technology enabling various biomedical applications such as remote drug deliveryand in vitro diagnostics. Contactless powering of such a microvalve is best addressed bynear-field inductive coupling due to its close proximity to the external interrogator. In thispaper, we propose the use of the same technique for secure remote interrogation andpowering of a human implantable, surface acoustic wave (SAW) correlation-based, passivemicrovalve. This is carried out by interrogating the microvalve with a Barkersequence-encoded BPSK signal. A numerical and experimental analysis of the biotelemetrylink for the microvalve was undertaken in the vicinity of numerical and physical humanbody phantoms, respectively. To accurately account for the path losses and to address thedesign optimization, the receiver coil/antenna was solved simultaneously withthe transmitter coil/antenna in the presence of a human body simulant usingthree-dimensional, high frequency electromagnetic FEM modelling. The received relativesignal strength was numerically and experimentally derived for a miniature (6 mm × 6 mm × 0.5 mm), square spiral antenna/coil when interrogated by a handheld8 cm × 5 cm × 0.2 cm square spiral antenna/coil in the near-field. Finally, the experimental results agreed wellwith the FEM analysis predictions and hence ascertained the applicability of the developedsystem for secure interrogation and remote powering of the newly proposed microvalve.