Autonomous multimodal implantable endoscopic capsule for the gastrointestinal tract
AUTOCAPSULE aims at demonstrating the viability of a technology for early diagnosis of Inflammatory Bowel Disease (IBD) and bowel cancer and for monitoring of treatment effectiveness at the primary or secondary points of care. The technology vision is based on an untethered autonomous capsule that is both implantable in the gastrointestinal (GI) tract for several weeks in order to monitor a specific area, and that can explore the GI tract for endoscopy in a point of care, through magnetic manipulation with an external robotic arm and limited expertise of the operator. The capsule is capable of multimodal sensing, including micro-ultrasound imaging, white light imaging, pH monitoring, and inflammation monitoring.
The project
MOTIVATION
The GI system is highly complex, subject to frequent external stimulus through eating and digestion, and carries an extremely high burden of disease: 15 – 40% of the European population report functional GI conditions. However, the range of conditions encompassed is too diverse a target for immediate action and we will therefore focus on inflammatory bowel disease (IBD) and colorectal cancer. Even for those diseases alone, the affected European populations are large, with colorectal cancer being the most common cancer in men (30% of all new cancers) and second most common in women (25% of all new cancers) with a total of about 350,000 cases in the EU in 2012. Moreover, the burden on healthcare systems is rising worldwide, with increased screening cited as the primary reason.
APPROACH
In the course of the AUTOCAPSULE project, two parallel tracks will be followed to demonstrate the technology vision, each focusing on a subset of the vision capsule features. One focuses on the development and demonstration of an untethered autonomous robotic capsule, capable of micro-ultrasound imaging and white light imaging. The other focuses on the development and demonstration of an implantable capsule, capable of operating with a sub-mW wireless power supply and of being parked in the GI tract for several weeks. AUTOCAPSULE will demonstrate capsules with partial complementary implementations of the technology vision and will show a path towards the fabrication and industrial development of the full vision capsule. The mentioned tracks are associated with two different modes of operation: a) during normal life, at home, and at work, the capsule is clipped in the GI tract to monitor vital functions (pH, temperature, local inflammation through EIS), and b) endoscopic imaging in primary or secondary point of care. The capsule is released and moved through magnetic manipulation with a robotic arm.
Robotic capsule demonstrator
The Robotic Capsule Demonstrator (RCD) will exploit advanced imaging techniques for high quality and high-resolution scanning of the entire GI tract, together with accurate robotic positioning and precise localization of the capsule while moving. In particular, white light imaging and micro-ultrasound array imaging will be combined to address the possibility to scan both the surface and the subsurface tissue structure of the entire GI tract with high quality and resolution. Robotic positioning will be achieved using external and internal permanent magnets and exploiting intelligent magnetic manipulation, combined with µUS imaging for accurate placement.
The 1st generation of the RCD will be wired, in order to be able to develop and test the µUS array, WLI modules, and the robotic positioning modules already at the start of the project, when wireless powering modules are still being developed. The 2nd generation of the RCD will be untethered, using wireless data transfer (WDT), that will allow high-speed communication with the external unit, and wireless power transfer (WPT), combined with a Power Management Integrated Circuit (PMIC), that will provide a sufficient power level during the entire operation. Both generations of RCDs will be tested also in vivo in porcine animal models.
- Robotic teleoperation
Magnetic manipulation is based on the interaction between magnetic fields, which is non-linear and varies significantly with the inter-magnetic distance. The Linear Parameter Varying (LPV) control strategy is considered in this approach. This technique is experimentally validated on the Magnetic Flexible Endoscope (MFE), an innovative magnetic colonoscope shown in Figure below, with the aim of stabilizing the magnetic endoscope to perform biopsies. A single soft-tethered endoscope equipped with an Internal Permanent Magnet (IPM) is actuated by means of a robotically manipulated External Permanent Magnet (EPM). The system is composed of a soft-tethered endoscope (the MFE) and a robotic manipulator to which an EPM is attached as the end-effector (for more details see reference).
Implantable capsule demonstrator
The Implantable Capsule Demonstrator (ICD) is inserted via endoscopy and is attached to the GI tract. This device will be small enough to be ingested. The multimodal sensing platform will include the measurement of pH and temperature, which are part of already accepted motility and transit time measurements. The device can also be inserted via endoscopy and it will have the ability to attach itself to the GI tract. The system will consist of a wireless power receiver, a multimodal sensing platform, and a miniature radio, operating in the Medical Implant Communication Service (MICS), and specifically designed to have an extremely small footprint by incorporating a novel clock generation scheme, not requiring a bulky crystal oscillator. The device will incorporate ultra-low-power readout electronics for electrochemical sensing which can be exploited to perform more advanced sensing.
Two generations of the ICD (ICD1 and ICD2) will be developed and tested, both operating with power in the range of 1-100 mW. ICD1 will have an on-board battery, which will limit the time of permanence of the capsule in the GI tract to 4 days. The second-generation ICD will operate via WPT supplied by a portable reader worn at the belt, enabling up to 30 days of permanence in the GI tract, and will have a smaller size, suited for better ingestion and lower patience discomfort, as well as to reach narrow regions of the tract.
Electronics and integration
Capsule miniaturization requires the integration of most electronic subsystems on silicon. Single Application Specific Integrated Circuits for each functional block will be designed, fabricated, and tested independently, for both RCDs and ICDs. The microprocessor interfaces with the different single integrated circuits to handle data transmission and communicate with the Power Management Integrated Circuits for proper delivery of the power budget.
