Conception et fabrication d'un microrobot sans fil autonome operant dans un milieu aqueux

There are several definitions of the word “robot”. One of them defines a robot as a device which can move and react to a stimulus to execute one or more dedicated tasks. Such a robot is endowed with a certain form of intelligence or a program which executes automatically without human intervention. Moreover, the design of a robot will be influenced by the environment in which it moves and by the functions which must be integrated to carry out some preset tasks.;In microrobotics, a major difficulty during the miniaturization of intelligent wireless robots is to feed them with power to support the four basic functions (intelligence, sensors, communication, actuation or displacement) while meeting volume constraints. Therefore, two principal approaches can be considered to reduce the robot dimensions. The first would be to increase the reception capacity and energy conversion. The second would be to decrease the electrical power requirements.;The first approach aims to collect the maximum energy which can be converted into electrical power inside the robot volume constraints and optimizing it. After reviewing the various power systems, we chose the photovoltaic cells as the electrical power system. Those can be integrated with the electronics of the robot. However, the energy provided by this type of power system depends in particular on the useful surface of the cell, but the latter must respect the volume constraints of the microrobot. To mitigate this problem, we propose a new architecture to increase the useful surface of a photovoltaic cell and, consequently the photonic current. The results of the experimental tests indicate that a power of ∼110 pW/µm2 is provided by our photovoltaic cell manufactured with this method.;As for the second approach, which aims at the minimization of the required energy, the same current produced by the photovoltaic module is time multiplexed to control the sensor and the telecommunication system using a new circuit architecture with minimal power consumption.;Such a miniature microrobot capable of interacting with the environment and communicating with an external computer has never been reported before. The communication system is based on the modulation of the magnetic field generated inside of the robot integrated coils into pulses whose frequency varies according to the ions concentration of the medium in which the microrobot moves. It was set a pulse frequency of 1 kHz to represent a low level of ions concentration and 2 kHz to represent a high level. An external computer interprets this magnetic pulses detected in order to change the microrobot trajectory.;The microrobot is manufactured using CMOS 0.13 µm technology, tests are conducted on the integrated photovoltaic cells which allow to measure a short circuit current of 2 µA flowing through the inductance and on an open voltage of 470 mV. More tests were performed using the MRI (Magnetic Resonance Imagery) to detect magnetic pulses generated by the communication system integrated to the microrobot. These results prove the functioning of the proposed self-powered telecommunication circuit. The MRI has captured images of the magnetic pulses generated by the telecommunication circuit integrated to the microrobot.