Depth Sensing for Improved Control of Lower Limb Prostheses
We developed, characterized, and validated an algorithm for recognizing stairs in the environment using data from a worn RGB-D sensor. The measures that we extracted from the environment, including the distance to the stairs, angle of approach, height, width, and depth of stairs, and stair count, were characterized and found to be highly correlated and accurate. Also, an estimate of when the user was approaching stairs was produced during an online walking test, which resulted in over 98% accuracy and a frame rate of more than 5 fps. We plan to fuse the environmental estimates with information obtained from EMG, kinetics, and kinematics for predicting the correct locomotion mode for an ankle-knee prosthesis.
New Methods to Monitor Stair Ascents Using a Wearable Pendant Device Reveal How Behavior, Fear, and Frailty Influence Falls in Octogenarians
We investigated whether a freely worn pendant inertial sensor, containing a triaxial accelerometer and a barometer, could be used to accurately identify stair ascent by 52 older adults in free living. Stair ascent could be identified using a decision tree, by scaling the barometer threshold to the rate of pressure change to accommodate both athletic and frail older adults with different cadences…
Heart Rate Detection during Sleep Using the Flexible RF Resonator and Injection-Locked PLL Sensor
The three types of radio frequency (RF) sensors for heart rate measurement on wrist, were the flexible RF single resonator, array resonators, and an injection-locked PLL resonator sensor. All three RF devices could detect heart rates at 0.2 to 1 mm distance from the skin of the wrist over clothes made of cotton fabric during sleep. Heart rates of 10 subjects were measured before and after sleep onset time using the device.
Omni-Directional Ultrasonic Powering for Millimeter-Scale Implantable Devices
We investigate ultrasonic powering of mm-scale devices with specific emphasize on the output power levels, efficiency, range, and omni-directionality. Omni-directionality is to some extent due to the symmetric receiver geometry and to a larger extent due to the reflection at different boundaries.
Real-time Neuroimaging and Cognitive Monitoring Using Wearable Dry EEG
In recent years, there have been significant advances in wearable, mobile, dry-electrode electroencephalography (EEG) systems. These are yielding exciting new possibilities for scientific research, clinical diagnostics and therapeutics, and brain-computer interfaces (BCI) outside the clinic or laboratory. However, these systems have been limited to a handful of channels mostly for applications of low-dimensional signal analysis in gaming and command control. Here we describe and evaluate the first high-resolution dry mobile BCI system supporting real-time artifact rejection, imaging of distributed cortical network dynamics, and inference of cognitive state with a 64-channel dry-electrode wireless EEG headset.
Closed-Loop Optogenetic Brain Interface
Brain-machine interface (BMI) techniques are developed to implement direct data communication links between the brain and artificial computers. The main objective in using BMI systems is to bypass or compensate possible damages in data processing pathways in the brain or to exchange data between the brain and the peripheral nervous system.