Implantable electronic chips are often used for sensing from nerve cells and internal organs for neuro scientific and therapeutic use [1][2][3]. These devices have the potential to improve quality of life of patients by providing continuous ambulatory monitoring of various bio-potential/biochemical signals and also provide necessary interventions (electrical stimulation, drug delivery etc.)[4]. Such implants are considered to be the future of medicine where more effective and precision interventions are necessary. Various implantable electrical devices are in the market for decades, such as heart pacemaker, cochlear implant and deep-brain stimulators stents[5][6].These large battery-operated devices mostly have a single setting with no user feedback. However, medical electronics of the future are expected to have bidirectional interface to the nervous system or organs. They will be ultra-small in size and with advanced closed loop-functionality. Peripheral nerve interfaces for chronic ailments (migraine, back-pain etc.), smart coronary stents or miniaturized cancer monitoring devices are examples of such technology[7].
Researchers in advanced implantable devices use various kinds of wireless technology (RF, ultrasonic or optical) to supply power and provide communication. All these methods have their own problems but none can guarantee a stable amount of power inside the human body. Hence, the implanted electronics should not only consume very low power but should also work at low supply voltage[8][9]. The requirements imposed on medical devices operating in the body are application specific and various constraints determines the available power, signal bandwidth, operating time, and communication range of the wireless telemetry link [10]. Furthermore, these extremely small implants (often in hundreds of micron size) and with no external components, have severe size restrictions. Although major advances have been achieved in the field of wireless communications from such implants, these circuit blocks remain as one of the most power-hungry ones. Data compression is another extremely critical block that has to make a trade-off between the transmission bandwidth and local power consumption, thus determining the overall power budget of the implant. The primary aim of the proposed project is to develop custom, novel ultra-low power digital cells for efficient signal processing (including data compression) and communication circuits for miniature wireless medical implant. This will be achieved through four main objectives:
O1: Propose suitable ultra-low power digital cells (memory and gates) and optimize their size.
O2: Implement relevant digital signal processing and communication blocks using the novel ultra-low power digital cells with optimized performance parameters.
O3: Fabricate, test and characterize the proposed communication and signal processing circuits.
O4:Incorporate the proposed circuit blocks within a complete wireless implanted sensor IC, (including analog data acquisition and RF transmission) and verify in saline measurements.
