We report the use of the amino polysaccharide chitosan for the immobilization and patterning of biomolecules on microfabricated surfaces. Chitosan is a biocompatible and biodegradable substance derived from chitin, which is the structural material in theexoskeleton of crustaceans. Chitosan has two key properties of interest to biologists and engineers alike. First, it has an abundance of primary amine groups which can be covalently coupled to various biomolecules. Second, it possesses pH-dependent network-forming properties. Below pH of 6.5, chitosan’s amine groups become protonated and positively charged, making it soluble in acidic conditions. At pH above 6.5 the amines become deprotonated, and chitosan forms an insoluble polymer network. This allows a film of chitosan to be deposited from solution onto a negatively charged electrode due to a localized region of high pH established near the electrode surface. This electrodeposition is a simple yet robust method of patterning biomolecules with significant advantages over traditional patterning techniques such as microcontact printing. We have demonstrated electrodeposited chitosan as an immobilization agent for DNA and several proteins. Amine-labeled DNA are coupled to chitosan by glutaraldehyde crosslinking and proteins are coupled by enzyme-activated genetically engineered tyrosyl residues. These coupling chemistries can be extended to other biomolecules as well. In addition, the biomolecule attachment can be reversed or completely blocked by passivating chitosan. With its electrodeposition property and its easily accessible amine groups, chitosan is an attractive material from both the microfabrication and biology perspective. Chitosan can be used for a wide range of devices as a spatially controllable interface between organic and inorganic components. The possible applications of chitosan include biosensors, drug delivery devices, and labs on a chip. In our work, we have successfully used chitosan for three — — different BioMEMS applications. One is an optical biosensor, in which chitosan is used to immobilize fluorescently labeled biomolecules on the facets of waveguides. Another is a micromechanical biosensor, in which chitosan immobilizes DNA on the surface of a microcantilever. The third one is a microfluidic device, in which chitosan is used to pattern biomolecules inside sealed microchannels. These devices demonstrate the simplicity and flexibility of chitosan-based biomolecular patterning

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Extracellular recordings of motor cortex (MI) neurons, using a chronically implanted multi-electrode array, promise to yield a high dimensional input signal to external devices such as a computer, exoskeleton or prosthetic arm. For the multi-electrode array to be used as a sensor for a neuromotor prosthesis (NMP), it is important that it continually record movement-related signals over long time periods. Recent studies have demonstrated that it is possible to continually record for up to 1.5 years from a sufficient number of MI neurons in monkeys to enable neural decoding of arm movement. Cyberkinetics Neurotechnology Systems Inc. has initiated an investigational device exemption (TOE) study investigating the safety and efficacy of the BrainGate™ Neural Interface System, a medical device that combines this sensor with data acquisition and processing devices to decode movement intent. This device is currently being investigated as a means for a quadriplegic person to operate a range of assistive technologies. Preliminary results from this case study provide evidence that (1) MI neurons remain active more than 3 years after spinal cord injury, (2) units can be recorded 6 months after surgery. This technology may benefit quadriplegic people by providing a new output pathway from the cortex, to control their muscles.

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We propose an algorithm used to obtain the information on stride length, height difference, and direction based on user’s intent during walking. For exoskeleton robots used to assist paraplegic patients’ walking, this information is used to generate gait patterns by themselves in on-line. To obtain this information, we attach an inertial measurement unit(IMU) on crutches and apply an extended kalman filter-based error correction method to reduce the phenomena of drift due to bias of the IMU. The proposed method is verifed in real walking scenarios including walking, climbing up-stairs, and changing direction of walking with normal.

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This paper reports the development of a power-assisted suit system actuated by ultrasonic motors. The proposed assisted suit is designed to support a caretaker performing nursing care tasks. The structure of the assisted suit has been designed to cover the caretaker’s motions as much as possible, and the suit is equipped with ultrasonic motors mounted in areas close to the joint rotation axis of the elbow, shoulder, waist, and knee. The suit frame is designed as an exoskeleton structure that can protect the wearer from bearing the suit’s weight because the foot part contacts the ground. A Phi60 double sandwich-type motors are used for the upper body part of the assisted suit. The torque of the double sandwich-type motor is about 3.8 times compared to the torque of the single sandwich-type motor. From the above results, the double sandwich-type motor is less space-saving but has high torque efficiency, and is therefore suitable as the actuator for the upper part of the assisted suit.

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The article presented the modeling and control of a pneumatically-powered gait orthosis (PPGO). According to the mechanism ofexoskeleton structure of pneumatic gait training device and pneumatic proportional system, an appropriate nonlinear process model was derived. In order to provide assistance as needed for supporting patient’s locomotion, a predictive fuzzy control (PFC) method was proposed based on the nonlinear dynamic model. This control algorithm is to evaluate the variables of PPGO based on fuzzy inference mechanism. The experiment of locomotion has been done to verify the effectiveness of proposed controller on the experimental setup of a pneumatically-powered gait orthosis.

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