Research in our group is centered on biomedical applications of MEMS (BioMEMS) and nanotechnology. This includes a variety of device and microsystems to address important clinical problems. Our group collaborates closely with physicians in order to transfer the technology to the clinic. Below is a list and brief description of the current projects pursued in our lab. For more information see the published literature or contact us.
Glaucoma is the leading cause of irreversible, yet preventable, blindness throughout the world (over 3 million Americans have glaucoma but only half of those know they have it). Glaucoma related blindness is a result of permanent damage to the optic nerve (optic neuropathy) for which elevated intraocular pressure (IOP, normal range 10-20mmHg) is the primary risk factor. As part of this project in collaboration with Indiana University School of Medicine, we are developing several implantable microdevices for wireless monitoring of IOP and an array of drainage devices for reducing the IOP.
In this project in collaboration with University of Minnesota (Neuroscince and Mechanical Engineering Departments), we are developing a battery-operated, high bandwidth, multi-channel wirelessl telemetry system for recording neural signals from awake behaving rats. The system is capable of transmitting 2.3Mbps of raw streaming data using the IEEE 802.11b protocol. In a typical application, the system was used to collect data from micro-wire electrodes implanted in the ventral striatum of an awake and behaving rat.
In this project, we are developing an array of hydrogel-based sensors and actuators for a variety of biomedical applications. These include wireless glucose sensors, microvalves for smart flow control, cantilever-based sensors, and hydrogel stamps for protein arrays. Our efforts in this area focus on fabricating methods and device designs to integrate environmentally sensitive hydrogels with microfluidic and MEMS components.
In this project in collaboration with University of Minnesota (Neuroscince Department), we are developing an electronically reconfigurable microfabricated tetrode array. We have designed and fabricated a 3D electronically reconfigurable tetrode with multiplexing capability for multi-neuronal recording. Each tetrode consists of four silicon shanks (40μm wide, 10μm thick, and 4.5mm in length) and each shank would have eight recording sites (10x10μm2 in size and 10μm separation). A three transistor analog multiplexer located next to each site allows each of the sites to be individually selected thus reducing the number of leads through the shank (to four for an eight channel electrode). Because the multiplexer allows selection of the recording location, an active electrode with n recording sites only requires {(log2 n )+1} leads. This will make possible the eventual creation of electrodes with hundreds of recording sites.
Measurement of ionizing radiation or “radiation dosimetry” is a frequent requirement in many areas of science, technology, and medicine. These include nuclear and particle physics, nuclear waste storage and management, environmental monitoring, radiology, and nuclear medicine. The ability to use wireless techniques for radiation measurement in conjunction with a miniature dosimeter will provide a valuable tool for radiation oncology. For example, miniature transponders can be implanted near a tumor for accurate wireless measurement of the received dosage during radiation therapy. In addition, if this capability can be combined with real-time tumor tracking, the benefits would be immense. In this project, in collaboration with Department of Radiation Oncology UT Southwestern Medical Center, we are developing MEMS-based implantable microsystems for radiation dosimetry and tumor tracking.
In this project in collaboration with University of Minnesota (ECE and Neuroscience Departments) we are developing a three-dimensional multi-channel wireless neural recording system. The system consists of a self-assembled active-pixel LED array that is connected to an array of folded electrodes. Each pixel element represents one recording site. The components are located on opposing sides of a silicon substrate and connected using through-holes. The pixel elements amplify and optically transmit the neuron signals that are recorded using the electrodes. A sequential self-assembly process is developed to fabricate assemble and electrically connect the pixel elements with the substrate. The recording electrodes will be micro machined out of silicon.
Manipulation of microscale droplets for moving, mixing, and sorting various samples and reagents on a chip (e.g. micro-total-analysis-systems (μ-TAS) or lab-on-a-chip) has attracted considerable attention recently. In particular, manipulation of free droplets on solid surfaces using dielectrophoresis, electrowetting on dielectric (EWOD), and surface tension gradient (e.g., thermocapillary or Marangoni effect) can provide versatile platforms with clear and significant applications in biotechnology and medical community (e.g., high throughput analyses and microassays). However, sample evaporation and contamination, the requirement for large voltages (electrowetting) or heat (thermocapillary), and complicated surface modifications have been typical drawbacks of the abovementioned methods. In this project, we are developing a simple method to manipulate free microdroplets using ferrofluid dynamics without substrate contamination and reduced evaporation. We have demonstrated a new way to manipulate microdroplets using oil-based ferrofluid, two strip magnets and a magnetic stirrer.
We are also working on several biomimetic sensors and actuators. These include biomimetic infrared and haptic interfaces and ratcheting biomimetic motion.
