Adaptive Power Regulation and Data Delivery for Multi-Module Implants

Emerging applications for implantable devices are requiring multi-unit systems with intrabody transmission of power and data through wireline interfaces. This paper proposes a novel method for power delivery within such a configuration that makes use of closed loop dynamic regulation. This is implemented for an implantable application requiring a single master and multiple identical slave devices utilising a parallel-connected 4-wire interface. The power regulation is achieved within the master unit through closed loop monitoring of the current consumption to the wired link. Simultaneous power transfer and full-duplex data communication is achieved by superimposing the power carrier and downlink data over two wires and uplink data over a second pair of wires. Measured results using a fully isolated (AC coupled) 4-wire lead, demonstrate this implementation can transmit up to 120 mW of power at 6 V (at the slave device, after eliminating any losses). The master device has a maximum efficiency of 80 % including a dominant dynamic power loss. A 6 V constant supply at the slave device is recovered 1.5 ms after a step of 22 mA

In-body wireline interfacing platform for multi-module implantable microsystems

The recent evolution of implantable medical devicesfrom single-unit stimulators to modern implantable microsys-tems, has driven the need for distributed technologies, in whichboth the implant system and functions are partitioned across mul-tiple active devices. This multi-module approach is made possiblethanks to novel network architectures, allowing for in-body powerand data communications to be performed using implantableleads. This paper discusses the challenges in implementing suchinterfacing system and presents a platform based on one centralimplant (CI) and multiple peripheral implants (PIs) using a cus-tom 4WiCS communication protocol. This is implemented in PCBtechnology and tested to demonstrate intrabody communicationcapabilities and power transfer within the network. Measuredresults show CI-to-PI power delivery achieves 70%efficiency inexpected load condition, while establishing full-duplex data linkwith up to 4 PIs simultaneously

Key Considerations for Power Management in Active Implantable Medical Devices

Within the rapidly advancing field of active implantable medical devices, power management is a major consideration. Devices that provide life critical (or avoiding life threatening) function require a dependable, always-on power source, for example pacemakers. There is then a trade-off with battery lifetime as to whether such devices employ a primary cell or rechargeable battery. With new applications requiring multi-module implants, there is now also a need for transmitting within the body from one device to another. This paper outlines the key considerations and the process to define and optimise the power management strategy. We then apply this to a case study application – developing an implanted, multi-module closed-loop neuromodulation device for the treatment of focal epilepsy