Force sensing has always been an important necessity in making decisions for manipulation. It becomes more appealing in the micro-scale context, especially where the surface forces become predominant. In addition, the deformations happening at the very local level are often coupled, and therefore providing multi-axis force sensing capabilities to microgripper becomes an important necessity. The manufacturing of a multi-axis instrumented microgripper comprises several levels of complexity, especially when it comes to the single wafer fabrication of a sensing and actuation mechanism. To address these requirements, in this work, an instrumented two-axis force sensing tool is proposed, which can then be integrated with the appropriate actuators for microgripping. Indeed, based on the task, the gripper design and shape requirements may differ. To cover wide needs, a versatile manufacturing strategy comprising of the separate fabrication of the passive and sensing parts was especially investigated. At the microscale, signal processing brings additional challenges, especially when we are dealing with multi-axis sensing. Therefore, a proper device, with efficient and appropriate systems and signal processing integration, is highly important. To keep these requirements in consideration, a dedicated clean-room based micro-fabrication of the devices and corresponding electronics to effectively process the signals are presented in this work. The fabricated sensing part can be assembled with wide varieties of passive parts to have different sensing tools as well as grippers. This force sensing tool is based upon the piezoresistive principle, and is experimentally demonstrated with a sensing capability up to 9 mN along the two axes with a resolution of 20 μN. The experimental results validate the measurement error within 1%. This work explains the system design, its working principle, FEM analysis, its fabrication and assembly, followed by the experimental validation of its performance. Moreover, the use of the proposed sensing tool for an instrumented gripper was also discussed and demonstrated with a micrograsping and release task.

Micro-assembly using glue is an industrial need, but at the microscale, the gluing process appears highly challenging. Especially when the thickness of the glue film is large relative to the size of components to be assembled. Moreover, the down-scaling of passive techniques used at the macroscale (such as using reference surfaces) are widespread, but require highly complex and dedicated procedures to reach the required precision (typically 1 $\mu$ m or below). To address this, we propose an original approach for micro-assembly that consists of using a thick film of glue (glue thickness typically $>$ 50 $\mu$ m) with an active microrobotic control. This approach enables us to have high precision positioning of the two components during the gluing task. The proposed approach appears highly versatile and flexible because it is independent of many parameters that usually influence gluing tasks. Several experiments without the use of the proposed approach show that the typical order of positional drift from curing could be of 5 to 15 $\mu$ m. Finally, experimental results using the proposed approach demonstrate that a positioning accuracy of 200 nm can typically be obtained, which validates the approach and suggests its potential interest to industry.

Fluidic systems enable actuation in various applications, such as automotive, medical, and industrial robotics. Miniaturized valves constitute a fundamental controlling element of modern fluidic systems, intriguing the interest of many researchers. This letter presents the design, implementation, and experimental validation of a miniaturized magnetorheological valve. The valve is highly efficient due to its capability of sustaining high loads with low energy consumption. This work includes the estimation strategy for the sustained load. Magnetorheological fluid is used both as an actuation fluid and as control medium. The inner iron core of the traditional magnetorheological valve is replaced with an AlNiCo-5 rod. The latter provides the possibility of magnetic energy storage, without continuous power supply. This changes the actuation mechanism from an electromagnet to an electropermanent magnet. The valve's capability to sustain pressure up to 1010 kPa, for a volume of 353 mm ³ , is demonstrated experimentally. The fluid flow rate when the valve is open is 459 mm ³ /s for a pressure difference of 993 kPa. The corresponding power consumption is negligible in steady-state condition, while consuming 15.3 mJ when activated and 6 mJ when deactivated. The experimental results also validate the possible tunability of the pressure sustaining capability of the valve.

This article presents a novel multiaxis μForce sensor with a range-to-resolution ratio of 55 000, which makes the sensing device highly useful for wide range of applications. The presented device relies on a sensing strategy where a 2-D encoded micropattern is encrypted to the mobile part of the compliant platform. This encoded pattern allows multiaxis visual sensing of displacements over a long range, whereas Fourier computations ensure subpixel interpolation leading to the high resolution. The device is fabricated on a silicon wafer by means of clean room technology to comply with both precision encoding requirements and reliable mechanical behavior. This article presents the design, modeling, and fabrication as well as the experimental validation of the multiaxis μForce-Torque sensor. A modeling strategy is proposed for an effective estimation of force/torque with its capability to adapt nonlinear stiffness evolution during the external loading. Experimentation demonstrates a sensing resolution of 2 μN over a validated range of 110 mN. The proposed sensor measures the force along the two planar axes, and also the torque along the axis orthogonal to the plane, thus, validating its axial decoupling capabilities.

Peripheral sensorimotor neuropathy among people with diabetes is one of the leading causes of foot ulceration. Plantar pressure is a significant parameter to control for the prevention of foot ulceration. A low cost sensing insole which can provide a reliable performance is therefore a demanding need. This work proposes a sensing insole which can be used for plantar pressure sensing for general use but also for decision making in active offloading. The device is based on piezoresistive principle and made from Polyester/Nylon 6 blend fabric comprising an array of 31 sensors, with their sensing range up to 960 $kPa$ corresponding to an active area of 78.5 $mm^{2}$ . The use of said fabric allows the needed flexibility, high abrasive resistance along with reliable performance. This work presents the sensing insole design, conception, packaging and the experimental validation.

Soft electrothermal actuators have been studied and proven to be useful in wide range of applications. Use of spin crossover materials in soft matrix for bilayer actuation is well documented with proven capability to deliver high flexibility and reliability. However, the use of these actuators is limited by their dependency on external sensors for position control. Such soft thermal actuators often exhibit hysteresis and non-linearity, making them challenging to operate in absence of sensor feedback. This work proposes a novel control scheme capable to effectively address the hysteresis thereby making it possible to actuate without dependency over external sensing. The proposed scheme allows the position control with the self-sensing without the need of any dedicated external sensor or any integrated sensing tool on the device. The device makes use of the resistance changes of the conductive layer which is primarily used to enable Joule heating of the electrothermal actuator. The presence of hysteresis has been effectively taken into account by a dedicated recursive temperature function based analytical model. Experimental studies validate the robustness of the model with a final error value less than 6.5 % . Different studies to track sinusoidal position over multiple cycles validate the repeatability of the performance. With an electric current of 850 mA , approximately 3.8 mm of displacement is controlled where the corresponding resistive change of 0.25 Ω is observed. The proposed strategy can also be helpful in performing other dedicated sensor-less actuations, which therefore strengthens the autonomy as well as applicability of such devices.