-A microrobot consisting of a polymer binded aggregate of ferromagnetic particles is controlled using a Magnetic Resonance Imaging (MRI) device in order to achieve targeted therapy. The primary contribution of this paper is the design of an adaptive backstepping controller coupled with a high gain observer based on a nonlinear model of a microrobot in a blood vessel. This work is motivated by the difficulty in accurately determining many biological parameters, which can result in parametric uncertainties to which model-based approaches are highly sensitive. We show that the most sensitive parameter, magnetization of the microrobot, can be measured using a Micro-Electro-Mechanical Systems (MEMS) force sensor, while the second one, the dielectric constant of blood, can be estimated on line. The efficacy of this approach is illustrated by simulation results.

As the field of biology becomes a more quantitative and predictive natural science, an increasing need for investigation and quantification of the mechanics of growth at individual cellular levels arises. This paper describes a microrobotic force-feedback based system and its application to the mechanical characterization of living, growing plant cells. The Cellular Force Microscope (CFM) is capable of performing the automated mechanical characterization of living plant cells in situ as these cells proliferate and grow. The microrobotic measurement system employs a single-axis capacitive MEMS microforce sensor capable of resolving forces down to 20 nN (1¿, at 10Hz). A multi-axis positioning system with 5 nm resolution position feedback is integrated into a complete system with a high-resolution optical microscope and a custom user interface for guiding an automated force-based measurement process. The CFM has been applied to characterize the mechanical properties of 20¿m wide Lilium pollen tubes while they grow at a rate of about 10 ¿m/min in growth medium. For the mechanical characterization of pollen tubes, loads up to 400 nN are applied that cause indentations up to 300 nm. The force-deformation data acquired show an increase in the observed stiffness from the tip to the apex demonstrating that CFM is a promising tool for better understanding the changing mechanics of living plant cell growth.

This paper presents the design, fabrication and characterization of the first microfabricated three-axis tunable force sensor with sub-micronewton measurement uncertainty. The sensing range can be electrically tuned from +/-20 μN to +/-200 μN while taking measurements, ensuring optimal sensor characteristics for a large variety of applications. Since the sensor has been pre-calibrated for the entire tuning range the exact sensor gain and its uncertainty is known. Real-time, three degree of freedom force feedback makes this sensor a valuable tool for micromanipulation.

This work describes the design of a capacitive multi-axis force-torque sensor for the monitoring of forces in the sub-milli-Newton and sub-micro-Newtonmeter range. This force range makes it a valuable tool for microrobotic applications. The sensor is experimentally investigated and calibrated. This is the first microfabricated 6-axis force-torque sensor that has been successfully developed.

This paper presents the design of a multi-axis micro force-torque sensor. The sensor is able to measure forces along two axes and a torque perpendicular to these forces. The load is measured by capacitive comb drives which provide a high sensitivity. The microfabrication process, the sensor readout electronics as well as the calibration procedure are presented. The sensor was used to measure the force and torque on a magnetically actuated microrobot. This microrobot is assembled from microfabricated nickel parts for directed drug delivery inside the human body. Precise knowledge load on the microrobot is required for accurate positioning and control of the robot. The three-axis micro sensor is used to simultaneously measure the forces and torques acting on the microrobot in a magnetic field and thus provides valuable data for magnetic control methods of microrobots.

This work reports on a system consisting of a MEMS (microelectromechanical system) gripper and an ultrasonic manipulator. The gripper is electrostatically actuated and includes an integrated force sensor measuring the gripping force. The device is monolithically fabricated using a silicon-on-insulator (SOI) fabrication process. The resolution of the force sensor is in the sub-micronewton range and, therefore, provides feedback of the forces that dominate the micromanipulation processes. A MEMS ultrasonic device is described which aligns small objects such as biological cells prior to manipulation with the gripper. The concept is demonstrated with polymer spheres, glass spheres and Hela cancer cells, thus providing a useful tool in micro-robotics and biological research