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Fluorescence biophotometry measurements require wide dynamic range (DR) and high sensitivity laboratory apparatus. Indeed, it is often very challenging to accurately resolve the small fluorescence variations in presence of high background tissue autofluorescence. There is a great need for smaller detectors combining high linearity, high sensitivity, and high-energy efficiency. This paper presents...
A new low-power custom integrated lock-in amplifier (LIA) with semi-digital automatic phase tuning is presented. The proposed LIA leverages a new semi-digital phase tuning peripheral loop to automatically align the relative phase of a low-amplitude input signal of known carrier with that of a reference signal to increase sensitivity while decreasing the power consumption of the LIA compared with previous...
Susceptibility-based negative contrast in magnetic resonance imaging (MRI) provides a mean to visualize magnetic microparticles. In the presence of a number of micropaticles in the field of view (FOV), the shape of the artifact is affected by the dipole-dipole interaction between the particles. Due to the limited spatial resolution of the clinical MR scanners, the exact positioning of the particles...
In this paper we present a hardware architecture with software implementation able to track free swimming single 2μm in diameter MC-1 bacterium. The computer vision system operates at up to 77 fps at full speed and up to 24 fps when recording full 512×512 pixels frame from coupled-charge device (CCD) array. Closed-loop control with lock-in tracking is achieved using the Otsu Segmentation Method (OSM)...
We introduce a method of motion control for bacterial microrobots using oxygen gradients. The bacteria (magnetotactic coccus strain MC-1) have a strong preference for a particular oxygen concentration and reverse swimming direction in order to remain at that oxygen concentration. At the same time, MC-1 consume oxygen, changing the dynamics of the system. We propose that we can use this behavior to...
Travelling inside the human body is an on-going scientific challenge. In this paper, we propose a new way of propelling robots inside the human body for gastro-intestinal applications actuated with the gradient field of an unmodified Magnetic Resonance Imaging (MRI) system. The robot is composed of a soft ferromagnetic head and a plastic tail attached together. This assembly is then placed in a bath...
The field of medical nanorobotics exploits nanometer-scale components and phenomena to enable new or at least to enhance existing medical diagnostic and interventional procedures. The best route for such miniature robots to access the various regions inside the human body is certainly the vascular network which is constituted of nearly 100,000 km of blood vessels. The variations in blood vessels diameters...
This paper describes the synthesis of thermoresponsive hydrogel bead for the implementation of untethered medical microrobots and other microdevices. These entities will have magnetic nanoparticles embedded, and will be targeted inside the body with an adapted Magnetic Resonance Imaging (MRI) system, and then triggered by the application of an alternating magnetic field for various functions, including...
Preliminary experiments showed that MC-1 magnetotactic bacteria (MTB) could be used for the delivery of therapeutic agents to tumoral lesions. Each bacterium can provide a significant thrust propulsion force generated by two flagella bundles exceeding 4pN. Furthermore, a chain of single-domain magnetosomes embedded in the cell allows computer directional control and tracking using a magnetic resonance...
This paper investigates the influence of the magnetosome's chain, the motility, and the bacterial cell of MC-1 magnetotactic bacteria (MTB) on the Magnetic Resonance imaging (MRI) contrast. Because of its embedded magnetic nanoparticles, that allow magnetic guidance and imaging contrast generation under MRI, magnetotactic bacteria are being considered for therapeutic drug delivery to tumors. In order...
Catheter navigation and placement through the arterial network is a major limitation for clinical procedure. In this article, a specific catheter tip and a modified clinical MRI scanner with an upgraded gradient system are used to steer a catheter through a single Y-shaped bifurcation. Safety aspects are analyzed to avoid the peripheral nerve stimulation (PNS) according to an empirical law of magnetostimulation...
Magnetic Resonance Targeting (MRT) uses MRI for gathering tracking data to determine the position of microscale entities with the goal of guiding them towards a specific target in the body accessible through the vascular network. At full capabilities, a MRT platform designed to treat a human would consist of a clinical MRI scanner running special algorithms and upgraded to provide propulsion gradient...
In magnetic resonance imaging (MRI), the susceptibility-based contrast provides a way to amplify the effects of a magnetic microparticle, whereas its volume is largely inferior to the spatial resolution of the system. This concept presents an approach to visualization by means of susceptibility artifact using ferromagnetic microparticles. In this work, the amount of the susceptibility artifact was...
Our group has previously demonstrated that magnetic nanoparticles (MNP) embedded in microrobots can be used for propulsion and tracking in the human vascular network while being guided by an MRI platform. Here, we show that the same magnetic nanoparticles can also be exploited to perform various functions including but not limited to hyperthermic drug release actuators. Specifically, we synthesized...
Bacteria can be used as computer-controlled bioactuators and means of propulsion for microrobots and other micro-scaled entities to accomplish precise operations as first proposed by our research group in [1] and demonstrated later experimentally in [2]. The last reference confirmed that the propulsion force provided by the flagella being connected to molecular motors embedded in the bacterial cell,...
The paper describes the choice of a thermoresponsive material for the implementation of untethered medical microrobots and other microdevices. These entities can be propelled at a specific location in the body using a Magnetic Resonance Imaging (MRI) system while being actuated for various functions such as the release of drugs by a volume change induced by hyperthermia of nanoparticles embedded in...
A real-time positioning and tracking technique for untethered devices or robots magnetically propelled by a clinical magnetic resonance imaging (MRI) system is described. The local magnetic field induced by the device, composed of a ferromagnetic material, is used as a signature to localize the device on three one-dimensional projections. A high-precision 3D circular-motion system was used to assess...
We show that a combination of various types of nanorobots will prove to be more important as we attend to enhance targeting in the smallest blood vessels found in the human microvasculature. As such, various interdependent concepts for the implementation of these different types of medical bio-nanorobots including nanorobots propelled in the microvasculature by flagellated bacteria to target deep...
The use of a clinical MRI system for propelling and controlling the displacement of a ferromagnetic core along a pre-planned path in the blood vessels has been validated experimentally by our group. The results of the experiment suggest that a MRI platform could not only be used as an imaging or diagnostic tool, but also as an interventional platform. One important medical intervention where such...
This paper presents a hybrid bacteria and microparticles detection platform based on a CMOS technology. Vertical face to face microelectrode arrays are implemented onto CMOS chips by connecting the metal and via layers together. A CMOS post-processing procedure based on Deep Reactive Ion Etching (DRIE) is used to release the microelectrodes and to construct microchannels in between. With medium flow...
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