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The Integrated Circuits and Optical Imaging Lab applies integrated circuit design and optical system design to create new instrumentation, particularly for biomedical applications. Some of the specific areas we work in are as follows.

  1. Complementary Metal Oxide Semiconductor (CMOS) imagers. Traditionally charge coupled device (CCD) based imagers have been used for biological imaging due to their sensitivity and noise superiority. However, CMOS imagers offer considerable improvements in system footprint, complexity, speed and power consumption. These advantages, in addition to the possibility of focal-plane processing, make CMOS imagers a compelling proposition for applications in clinical usage (portable, point-of-care imaging instruments) as well as in basic biological research (unrestrained animal imaging, high throughput miniaturized systems). The challenge is to use innovative analog and mixed-signal integrated circuit design to boost the performance of CMOS imagers.

  2. Tissue Oxygenation in Deep Brain Structures. Oxygen saturation is an important marker of brain activity and can be measured using optical imaging of intrinsic signal. However, current imaging methods are either limited to the surface of the brain, or suffer from poor spatial and/or temporal resolution. To break these limits, we are developing a single fiber optical system to measure the oxygen saturation from a small volume of tissue in deep brain structures by implanting the fiber in to the area of interest. In collaboration with the lab of Dr. Jeff Dunn The system has been shown to quantify oxygen saturation in a scattering tissue phantom and has the potential to be used in long-term oxygen saturation monitoring in freely-moving animals.

  3. Miniaturized Self-Contained Imaging Systems. Current research and diagnostic imaging systems are typically large, expensive benchtop devices. In order to take the full benefit of single-chip CMOS imagers, imaging systems also need to be redesigned. The challenge here is to incorporate all aspects on an optical imaging system - illumination, image formation, image sensing, data storage and power supply - into a small footprint device. Particularly we are interested in creating miniaturized imaging systems that will enable imaging the brain in untethered, freely-moving small animals such as mice. Such instrumentation can have far-reaching impact because it allows the study of brain morphology and physiology continuously and chronically without the fog of anesthesia. A wide range of behavioral experiments can be designed to better our understanding of the brain.

  4. Ca2+ dynamics in deep brain structures. Certain fluorescent proteins have been engineered to report cellular dynamics, such as calcium concentration. These measurements are often indicators of increased neural activity, and can be used in a variety of experimental contexts to help understand how the brain works. Through collaboration with the lab of Dr. Jaideep Bains, we're developing a single optical fiber system to enable investigation of activity at the population level in a transgenic mouse. The system has so far been applied to study spectral characteristics of the GCaMP calcium indicator in both slice preparations and in deep brain structures of an awake and behaving animal.

  5. Cortical effects of Deep Brain Stimulation (DBS). Recent studies have demonstrated that changes in cortical activity due to DBS are important in its therapeutic effect. In collaboration with the lab of Dr. Zelma Kiss, we are using these changes in cortical activity as a marker to study two things in a rat model - 1) optimal stimulation parameters (amplitude, pulse width and frequency) for DBS therapy and 2) Long term effects of DBS. We are studying optimal parameters in anesthetized animals using electrophysiology and intrinsic optical imaging. To investigate the long term effects of DBS freely moving animals, we will perform stimulation using miniaturized constant current stimulators and intrinsic optical imaging using miniaturized imaging systems being developed in the lab.

  6. Role of muscle synchronization in endurance and fatigue. The principle of bipolar potential electromyography (EMG) has been the same for decades. Signals are acquired in either a monopolar or bipolar configuration with a high impedance differential voltage amplifier. Recent research describes a new method to detect muscle activity using current. It has been shown that the current-amplifier configuration is essential to quantify the synchronization of muscle activity. We are working on a new design for a current-amplifier that improves the performance of existing instrumentation. In collaboration with the lab of Dr. Benno Nigg, we will use the amplifier to investigate the role of muscle synchronization, as measured by coherence, in performance and fatigue in a cycling model.