Riccardo Carta

Wireless powering for a self-propelled and steerable endoscopic capsule for stomach inspection

This paper describes the integration of an active locomotion module in a wirelessly powered endoscopic capsule. The device is a submersible capsule optimized to operate in a fluid environment in a liquid-distended stomach. A 3D inductive link is used to supply up to 400mW to the embedded electronics and a set of 4 radio-controlled motor propellers. The design takes advantage of a ferrite-core in the receiving coil-set. This approach significantly improves the coupling with the external field source with respect to earlier work by the group. It doubles the power that can be received with a coreless coil-set under identical external conditions. The upper limit of the received power was achieved complying with the strict regulations for safe exposure of biological tissue to variable magnetic fields. The wireless transferred power was proven to be sufficient to achieve the speed of 7cm/s in any directions. An optimized locomotion strategy was defined which limits the power consumption by running only 2 motors at a time. A user interface and a joystick controller allow to fully drive the capsule in an intuitive manner. The device functionalities were successfully tested in a dry and a wet environment in a laboratory set-up.

Wireless power and data transmission strategies for next-generation capsule endoscopes

Capsular endoscopy is becoming increasingly popular as an alternative to traditional gastro-intestinal (GI) examination techniques. However, the breakthrough of these devices is hindered by the limited amount of power that can be stored in a tiny pill. Most commercial devices use two watch batteries that can only provide an average power of 25 mW for about 6 h, certainly not sufficient for advanced robotic features. A dedicated inductive powering system, operating at 1 MHz to limit the human body absorption, has been developed which was proven to support the transfer of over 300 mW. The system relies on a condensed set of orthogonal ferrite coils, embedded in the capsule, and an external unit based on a Helmholtz coil driven by a class E amplifier. Control data can be sent through the inductive link by modulating the power carrier, whereas a dedicated high data rate RF link is used to transfer the images from the capsule to the base station. Besides evaluating the compatibility with radio transmission, several demonstrators were assembled combining the wireless powering system with various locomotion strategies and LED illumination. This paper describes the design and implementation of the inductive powering system, its combination with data transmission techniques and the testing activity with other capsule-dedicated modules.

A Differential Pressure Approach to Spirometry

This paper presents the design, implementation and measurements of a spirometer based on differential pressure sensing. A system which fulfills the last medical standard specifications has been designed exploiting the Venturi tube principle. A fully operating prototype has been tested, and data have been subsequently analyzed. Air flows up to 14 L/s can be measured with an accuracy of 0.2 L/s. Data acquisition software and user interface were developed.

Wireless Power and Data Transmission for Robotic Endoscopic Capsules

Robotic capsular endoscopy is nowadays a really hot topic. Scientists are fascinated by the idea of developing an integrated tool that travels through the human body while sending images, measuring biomedical parameters and performing therapeutic activity. Doctors actively support this futuristic solution aiming at non invasive examination and therapy. Patients appreciate the idea of swallowing a capsule that performs medical examinations without any pain or discomfort. Although technology has obtained results unthinkable only a few years ago, the main issue is the dramatic lack of energy in the capsule. Up to date commercial capsules are purely passive devices relying on batteries that provide a mere 25 mW for 6 to 8 hours. A promising approach to overcome energy shortage is wireless powering. A condensed set of orthogonal coils inside the capsule can retrieve more than 300 mW from an external magnetic field, without any time limitation. This solution allows the integration in the capsule of highly consuming modules such as diagnostic tools, actuators, a better camera and a high data-rate transmitter. This work presents an overview of this powering solution and proposes a few examples of system integration.

In vitro cytotoxicity testing and the application of elastic interconnection technology for short-term implantable electronics

An electronic device was fabricated consisting of 2 flexible electronic circuit islands, interconnected by a 7 cm long elastic interconnection, which could be elongated for at least 50%. This interconnection was based on gold conductor tracks following a 2-D spring pattern, embedded in a biocompatible silicone elastomer. The complete device was embedded in the same silicone elastomer. An in vitro cytotoxicity extraction test, executed on small test-samples in accordance with the ISO 10 993-1 guidelines, revealed that the applied silicone encapsulation to these samples functioned as a good seal for at least 8 days.

Energy autonomous wireless filling detector

A wireless energy autonomous filling yarn detector for an air jet weaving machine has been designed, built and tested on an opto-mechanical mock-up of the weaving loom. The energy autonomous operation of the detector is sustained by a commercially available vibrational energy harvester which can deliver several mW to the sensor node. The sensor node relies on the combination of three main blocks: an optical detector, a microcontroller and a wireless transceiver. The first block is responsible for the detection of the filling yarn, the wireless transceiver for the communication with the base station integrated with the weaving machine controller, while the microcontroller supervises and regulates the overall system operation. The node has been designed and assembled selecting commercial off-the-shelf components among the most power efficient available on the market. In order to further limit the power consumption, the trigger to wake up the sensor and start a measurement relies on the same optical link used for the filling yarn detection. After a yarn detection, the system is configured to communicate the event to the base station and go back to sleep. It has been demonstrated that at a machine speed of 1500 rpm, the vibrational energy harvester can harvest a power of 11 mW while the sensor node board only consumes 2.5 mW on the average.