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This paper presents the design, fabrication, control and testing of the third generation prototype of a novel, one degree of freedom (DOF) Variable Resistance Hand Device (VRHD) that was designed for isotonic, isokinetic, and variable resistance grasp and release exercises. Its principle functionality is derived from an electro-rheological fluid based controllable damper that allows continuously variable modulation of dynamic resistance throughout its stroke. The VRHD system consists of the patient actuated device, the control electronics and software, the practitioner graphical interface and the patient's virtual reality game software. VRHD was designed and experimentally shown to be fully Magnetic Resonance Imaging (MRI) compatible so that it can be used in brain MR imaging during handgrip rehabilitation.

New actuators are greatly demanded today in order to develop magnetic resonance imaging (MRI)-compatible mechatronic systems capable of extended and improved capabilities. They are particularly needed for MRI-guided interventional or rehabilitation procedures. Actuators based on dielectric elastomers, a specific class of electroactive polymers, appear as suitable candidates for new MRI-compatible technologies, due to their intrinsic material properties and working principle. This paper presents the first investigation on the MRI compatibility of a recently developed linear contractile actuator made of a silicone elastomer. The assessed absence of any degradation of both the actuator electromechanical performance in the MRI environment and the quality of images acquired from a phantom demonstrated the MRI compatibility of the actuator. These results suggest the suitability of this soft actuation technology as a possible new entry in the class of MRI compatible mechatronic systems.

This paper presents the design, fabrication and testing of a novel, one degree of freedom (DOF) magnetic resonance compatible smart hand interfaced rehabilitation device (MR_CHIROD v.2), which may be used in brain magnetic resonance (MR) imaging during handgrip rehabilitation. The device consists of three major subsystems: a) an ERF based resistive element; b) handles and c) two sensors, one optical encoder and one force sensor, to measure the patient induced motion and force. MR_CHIROD v.2 is designed to resist up to 50% of the maximum level of gripping force of a human hand and be controlled in real time. Our results demonstrate that the MR environment does not interfere with the performance of the MR_CHIROD v.2, and, reciprocally, its use does not cause fMR image artifacts. The results are encouraging in jointly using MR_CHIROD v.2 and brain MR imaging to study motor performance and assess rehabilitation after neurological injuries such as stroke.

The authors present the first design, fabrication and testing results from an electrohydrodynamic (EHD) micropump on a flexible Parylene-C substrate. Parylene-C membranes with their excellent properties are rarely used yet are very promising candidates as flexible substrates. Low power on-chip micropumps are needed in various fields including biotechnology and cryogenic cooling. Furthermore, being fabricated on a flexible Parylene substrate, they can be utilized in commercial applications including wearable textiles. Pumping pressures of up to 490Pa (@30 Volts) with a flow velocity of 190mm/min (@20 Volts) is measured using isopropanol (IPA) fluid. The micropump has no moving parts and occupies a volume of only 5mmtimes7mmtimes80mum. This is the first instance of a low power EHD micropump fabricated on a flexible Parylene-C substrate.

This paper presents the design, fabrication and preliminary tests of a novel, one degree of freedom, MR compatible, computer controlled, variable resistance hand device that will be used in fMRI studies of the brain and motor performance during rehabilitation after stroke. The device consists of four major subsystems: a) the electro-rheological fluid (ERF) resistive element; b) the gearbox; c) the handles and d) the sensors: one optical encoder and one force sensor attached to the ERF resistive element's shaft to measure the patient induced motion and force, respectively. A key feature of the device is the use of electro theological fluids (ERF) to achieve resistive force generation. ERFs are fluids that experience dramatic changes in rheological properties, such as viscosity or yield stress, in the presence of an electric field. Using the electrically controlled rheological properties of ERFs, compact resistive elements with an ability to supply high resistive torques in a controllable and tunable fashion, have been developed. Our preliminary tests demonstrate that the device can apply, on a human hand holding the device handles, resistive forces that exceed 150 N. In addition the activated ERF maintain its properties in the magnetic environment without creating degradation of the MR images. The results are encouraging in combining functional magnetic resonance imaging methods, with MR compatible robotic devices for improved effectiveness of rehabilitation therapy.