Bio-hybrid devices, which integrate biological cells with synthetic components, have opened a new path in miniaturized systems with the potential to provide actuation and control for systems down to a few microns in size. Here, we address the challenge of remotely controlling bio-hybrid microswimmers propelled by multiple bacterial cells. These devices have been proposed as a viable method for targeted drug delivery but have also been shown to exhibit stochastic motion. We demonstrate a method of remote magnetic control that significantly reduces the stochasticity of the motion, enabling steering control. The demonstrated microswimmers consist of multiple Serratia marcescens (S. marcescens) bacteria attached to a 6 μm-diameter superparamagnetic bead. We characterize their motion and define the parameters governing their controllability. We show that the microswimmers can be controlled along two-dimensional (2-D) trajectories using weak magnetic fields (≤10 mT) and can achieve 2-D swimming speeds up to 7.3 μm s(-1). This magnetic steering approach can be integrated with sensory-based steering in future work, enabling new control strategies for bio-hybrid microsystems.

This paper presents a new high speed vision system using an asynchronous address-event representation camera. Within this framework, an asynchronous event-based real-time Hough circle transform is developed to track microspheres. The technology presented in this paper allows for a robust realtime event-based multiobject position detection at a frequency of several kHz with a low computational cost. Brownian motion is also detected within this context with both high speed and precision. The carried-out work is adapted to the automated or remote-operated microrobotic systems fulfilling their need of an extremely fast vision feedback. It is also a very promising solution to the micro physical phenomena analysis and particularly for the micro/nanoscale force measurement.

Abstract:Optical tweezers are a powerful tool for micromanipulation and measurement of picoNewton sized forces. However, conventional interfaces present difficulties as the user cannot feel the forces involved. We present an interface to optical tweezers, based around a low-cost commercial force feedback device. The different dynamics of the micro-world make intuitive force feedback a challenge. We propose a coupling method using an existing optical tweezers system and discuss stability and transparency. Our system allows the user to perceive real Brownian motion and viscosity, as well as forces exerted during manipulation of objects by a trapped bead.

Abstract-Laser induced convection flows is a new and promising method to achieve better manipulation of mesoscale objects (above 1 µm and below 500 µm) in a liquid medium. The temperature gradient created by laser absorption generates natural and thermocapillary (or Marangoni) convection flows. These flows are used to perform the manipulation itself. In this paper, we demonstrate for the first time that large and heavy particles can be dragged using the Marangoni convection flows. Experiments based on these phenomena show that fast and accurate underwater micromanipulation of particles up to 280 µm is possible using only a convergent 1 480 nm laser beam.

This paper is the first review of haptic optical tweezers, a new technique which associates force feedback teleoperation with optical tweezers. This technique allows users to explore the microworld by sensing and exerting picoNewton-scale forces with trapped microspheres. Haptic optical tweezers also allow improved dexterity of micromanipulation and micro-assembly. One of the challenges of this technique is to sense and magnify picoNewton-scale forces by a factor of 10(12) to enable human operators to perceive interactions that they have never experienced before, such as adhesion phenomena, extremely low inertia, and high frequency dynamics of extremely small objects. The design of optical tweezers for high quality haptic feedback is challenging, given the requirements for very high sensitivity and dynamic stability. The concept, design process, and specification of optical tweezers reviewed here are focused on those intended for haptic teleoperation. In this paper, two new specific designs as well as the current state-of-the-art are presented. Moreover, the remaining important issues are identified for further developments. The initial results obtained are promising and demonstrate that optical tweezers have a significant potential for haptic exploration of the microworld. Haptic optical tweezers will become an invaluable tool for force feedback micromanipulation of biological samples and nano- and micro-assembly parts.

The optical trap is a powerful non-contact approach for manipulating micron sized objects. Teleoperation of optical tweezers can be performed by coupling with a haptic interface, which allows an efficient robotic device to control positions and get force feedback. This provides users direct and intuitive microscopic interactions. The major difficulty in order for haptic devices to generate a reliable tactile sensation lies in its high frequency requirement of more than 1 kHz. This paper presents a fast force feedback teleoperation system for optical tweezers that attains this high frequency. The used force sensor is a novel event-based camera that transmits output as a continuous stream of asynchronous temporal events thus enabling high speed event-based visual processing. This new sensor is compared to a conventional frame based one to show advantages of our setup. A complex task of exploiting three dimensional target surface is performed demonstrating the robustness and efficiency of the presented method. This is the first time microspheres are used to touch targets of arbitrary form and color, which may interest broad-reaching biological and physical applications.

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