Purpose Retinal microsurgery requires extremely delicate manipulation of retinal tissue where tool-to-tissue interaction forces are usually below the threshold of human perception. Creating a force-sensing surgical instrument that measures the forces directly at the tool tip poses great challenges due to the interactions between the tool shaft and the sclerotomy opening. Methods We present the design and analysis of a force measurement device that senses distal forces interior to the sclera using 1-cm long, 160 µm diameter Fiber Bragg Grating (FBG) strain sensors embedded in a 0.5 mm diameter tool shaft. Additionally, we provide an algorithm developed to cancel the influence of environmental temperature fluctuations. Results The force-sensing prototype measures forces with a resolution of 0.25 mN in 2 DOF while being insensitive to temperature. Conclusion Sub-millinewton resolution force sensors integrated into microsurgical instruments are feasible and

The electrical resistivity of a thermoresponsive polyurethane shape-memory polymer ͑SMP͒ filled with micron sized Ni powders is investigated in this letter. We show that, by forming conductive Ni chains under a weak static magnetic field ͑0.03 T͒, the electrical conductivity of the SMP composite in the chain direction can be improved significantly, which makes it more suitable for Joule heat induced shape recovery. In addition, Ni chains reinforce the SMP significantly but their influence on the glass transition temperature is about the same as that of the randomly distributed Ni powders.

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MRI and MRSI have the potential to identify cancer foci and direct TRUS in patients with a previous negative TRUS biopsy. Further, larger studies are required to quantify the amount of benefit.