The objective of this study is to evaluate the estimation accuracy of the wearable ground reaction force measurement system. We assumed to use the device for the rehabilitation of fracture patients. They usually limited the floor reaction force during the rehabilitation, however, there are no proper devices to measure the force. Conventionally patients step a weight scale to remember the force by their sense. Wearable and low price systems might increase the quality of the rehabilitations. Twelve thin and small sensors were attached under the shoe sole and these output data were used as explanatory variables to estimate the ground reaction force. Test subjects were asked to put on the device and walk in two ways;normally and reducing the ground force by using handrails, as during rehabilitation. Measured data of eight healthy test subjects were divided in half to teacher data and test data, including four test subjects respectively. The regression equation was created as the linear combination of the sensor outputs with the coefficients to minimize the root mean square error. Although the previous research using a similar system required the regression equation for each test subject, we used a general equation which is applicable to any subject. As a result, the average error was 2.79 kgf for teacher data and was 3.64 kgf for test data. One test subject included in the test data showed remarkably large error, 8.99 kgf on average, while the average error of the other three test subjects was 3.09 kgf. The result indicated that it might be difficult to remove the individual differences, and some test subjects would cause unignorable estimation error. However, it might be accurate enough relative to the conventional method of limiting the ground reacting force during the rehabilitation of fracture patients. It is our future task to reduce the error and improve the usability by extending the test subjects to discuss when the error increase or applying this system for the clinical trials.

Laser microdissection (LMD) is a method for isolating a specific region of a tissue sample or a specific cell using an ultraviolet (UV) laser beam under a microscope. Various biomolecules, such as nucleic acids and protein molecules, can be purified and extracted from isolated biological specimens, which can be used for molecular biological analysis. The laser beam scan on the sample plane to cut out arbitrary areas of the target sample has been conventionally performed using an XY motorized stage or a set of two deflection prisms. In addition to the usability of these conventional laser scanning components, there is a concern about thermal damage to the sample caused by UV laser irradiation. This paper reports on the development of microelectromechanical system (MEMS) mirror-type LMD instrumentation for reducing thermal damage by high-speed laser scanning. We compare the laser deflection components used in the two major laser scanning methods:raster and vector scans. Then, we detail the operating principle of the electrostatic-type MEMS mirror used in this study and the development of our instrumentation. The MEMS mirror deflection (non-resonant mode) is controlled by a vector scan operation and is not synchronized with laser pulse irradiation. The developed instrumentation demonstrates a high-speed laser scan, which is several tens of times faster than that of conventional LMD instrumentation. We then demonstrate the LMD of a pig heart muscle slice and confirm that a higher laser pulse rate lowered the number of scans required to complete the LMD. Further, we discuss the laser irradiation-induced thermal damage to the target tissue in association with the scan speed and describe the simulation performed to estimate the number of laser scans to complete microdissection by varying the laser scan speed and repetition rate. The simulation results indicate that our instrumentation affords LMD with reduction in sample thermal damage and minimizes the number of laser scans and the process time. The characteristics of the instrumentation, including the ability to reduce sample thermal damage, a compact and simple structure, unitization capability, high compatibility with optical microscopy, and cost effectiveness offer an attractive alternative to conventional, commercially available LMD instrumentation.