Secure wireless actuation of an implanted microvalve for drug delivery applications

The capability to wirelessly control fluid flow through a microvalve can emerge as an attractive technology enabling various biomedical applications such as remote drug delivery and in vitro diagnostics. Contactless powering of such a microvalve is best addressed by near-field inductive coupling due to its close proximity to the external interrogator. In this paper, we propose the use of the same technique for secure remote interrogation and powering of a human implantable, surface acoustic wave (SAW) correlation-based, passive microvalve. This is carried out by interrogating the microvalve with a Barker sequence-encoded BPSK signal. A numerical and experimental analysis of the biotelemetry link for the microvalve was undertaken in the vicinity of numerical and physical human body phantoms, respectively. To accurately account for the path losses and to address the design optimization, the receiver coil/antenna was solved simultaneously with the transmitter coil/antenna in the presence of a human body simulant using three-dimensional, high frequency electromagnetic FEM modelling. The received relative signal strength was numerically and experimentally derived for a miniature (6 mm x 6 mm x 0.5 mm), square spiral antenna/coil when interrogated by a handheld 8 cm x 5 cm x 0.2 cm square spiral antenna/coil in the near-field. Finally, the experimental results agreed well with the FEM analysis predictions and hence ascertained the applicability of the developed system for secure interrogation and remote powering of the newly proposed microvalve.