The Neural Interfaces & MicroSystems Laboratory at DGIST is dedicated to creating new technologies that can interface the human body with artificial technical systems (e.g., computers, next-generation robots, prosthetic arms and legs, neural stimulators) as well as meet the needs in clinics and hospitals to diagnose, monitor, rehabilitate and treat neurological diseases and disorders. Our research focuses are the development of 2D and 3D flexible neural interfaces including brain interfaces, peripheral nerve interfaces, retina interfaces; polymer-based microfabrication technologies for soft bio-MEMS (micro-electro-mechanical system); and electrophysiology tools for zebrafish. Current research topics of our laboratory include

• Brain interfaces to study the brain function and toward brain-machine interface (BMI)

• Peripheral nerve interfaces for neurally-controlled robotic arms with sensory feedback

• Retinal implants to restore the vision

• Implantable magnetic stimulation to modulate the brain function

• Stretchable and wearable sensors for bio-signal detection and monitoring

• Polymer-based soft bio-MEMS technologies

• Zebrafish EEG/EMG/ECG and their application for new drug development

For more information on the research topics of our lab, read the articles below.

We develop novel neural microelectrodes that can be implanted in the body, to detect signals from or to electrically stimulate the brain, peripheral nerves, and the retina. The microelectrodes are fabricated using MEMS (micro-electro-mechanical system) technologies based on polymers or polymer/silicon hybrid structures, for improved biocompatibility. The developed microelectrodes have been investigated for long-term in-vivo use.

Related publications

1. "Development of a Polydimethylsiloxane‐Based Electrode Array for Electrocorticography," Advanced Materials Interfaces, Nov. 2020.

2. "Fabrication of Subretinal 3D Microelectrodes with Hexagonal Arrangement," Micromachines, 2020.

3. "A 3D flexible microelectrode array for subretinal stimulation," J. Neural Engineering, 2019.

4. "An Intrafascicular Neural Interface with Enhanced Interconnection for Recording of Peripheral Nerve Signals," IEEE Trans. Neural Systems and Rehabilitation Engineering, 2019.

5. "Recording nerve signals in canine sciatic nerves with a flexible penetrating microelectrode array," J. Neural Engineering, 2017.

6. "Selectivity and Longevity of Peripheral-Nerve and Machine Interfaces: A Review," Frontiers in Neurorobotics, 2017.

7. "Polymer-based interconnection cables to integrate with flexible penetrating microelectrode arrays," Biomed Microdevices, 2017.

8. "Long-term characterization of neural electrodes based on parylene-caulked polydimethylsiloxane substrate," Biomedical Microdevices, 2016.

9. "MEMS-based microelectrode technologies capable of penetrating neural tissues," Biomedical Engineering Letters, 2014.

10. "Fabrication of a Flexible Penetrating Microelectrode Array for Use on Curved Surfaces of Neural Tissues," J. Mircromechanics & Microengineering, 2013.

11. "A Largely Deformable Surface Type Neural Electrode Array based on PDMS," IEEE T. Neural Systems & Rehabilitation Engineering, 2013.

We develop implantable magnetic and optical neural stimulation methodologies in addition to traditional electrical stimulation. Electrical stimulation has been the standard method to stimulate neural tissues but also has some disadvantages. To overcome the limitations of electrical stimulation, we explore the feasibility of implantable magnetic and optical stimulation methods in-vitro as well as in-vivo.

Related publications

1. "Planar coil-based contact-mode magnetic stimulation: synaptic responses in hippocampal slices and thermal considerations," Scientific Reports, 2018.

2. "Computational study on the thermal effects of implantable magnetic stimulation based on planar coils," IEEE T. Biomedical Engineering, 2016.

3. "Near Infrared Stimulation on Globus Pallidus and Subthalamus," J. Biomedical Optics, 2013.

We develop novel electrophysiological tools to detect bioelectric signals from zebrafish, including EEG, ECG and EMG signals. These zebrafish-specific techniques can be useful for mass screening of drug candidates as zebrafish is a very economical and efficient animal model. We currently monitor EEG signals from zebrafish after treatment of anti-epileptic drugs.

Related publications

1. "A Microfluidic System for Stable and Continuous EEG Monitoring from Multiple Larval Zebrafish," Sensors, 20, 5903, Oct. 2020.

2. "An EEG system to detect brain signals from multiple adult zebrafish," Biosensors and Bioelectronics, 2020.

3. "High-throughput zebrafish intramuscular recording assay," Sensors and Actuators B, 2020.

4. “A zebrafish model of nondystrophic myotonia with sodium channelopathy,” Neuroscience Letters, 2020.

5. "Zebrafish as an animal model in epilepsy studies with multichannel EEG recordings," Scientific Reports, 2017.

6. "A 3D-Printed Sensor for Monitoring Biosignals in Small Animals," J. Healthcare Engineering, 2017.

7. "Zebrafish Needle EMG: a New Tool for High-throughput Drug Screens," J. Neurophysiology, 2015.

We develop novel fabrication techniques to pattern thin-film metals or silver nanowires based on flexible and/or stretchable polymeric substrates. We develop a technique to create soft and flexible 3D structures with embedded conductive patterns in the micrometer scale. The fabricated 3D structures can be used in a wide range of biomedical applications such as neural interfaces, drug delivery systems, soft sensors and actuators, to soft robotics.

Related publications

1. "Transformation of 2D Planes into 3D Soft and Flexible Structures with Embedded Electrical Functionality," ACS applied materials & interfaces, 2019.

2. "Large-sized out-of-plane stretchable electrodes based on poly-dimethylsiloxane (PDMS) substrate," Applied Physics Letters, 2014.

3. "Crack-free and reliable lithographical patterning methods on PDMS substrate," J. Mircromechanics & Microengineering, 2013.

We develop novel fabrication techniques to pattern thin-film metals or silver nanowires based on flexible and/or stretchable polymeric substrates. We expand the application of these fabrication techniques for developing new flexible printed circuit boards (FPCB) and wearable/patchable bio-signal monitoring sensors towards smart health-care system in future.

Related publications

1. "A silver nanowire-based fexible pressure sensor to measure the non-nutritive sucking power of neonates", Micro and Nano Systems Letters, 2020.

2. "A wearable device to measure the palmar grasp reflex of neonates in neonatal intensive care unit," Sensors and Actuators A, 2020.

3. "A batteryless, wireless strain sensor using resonant frequency modulation," Sensors, 2018.

4. "Annealing Effects of Parylene-Caulked Polydimethylsiloxane as a Substrate of Electrodes," Sensors, 2016.

5. "A method to pattern silver nanowires directly on wafer-scale PDMS substrate and its applications," ACS Applied Materials & Interfaces, 2016.

6. "Large-sized out-of-plane stretchable electrodes based on poly-dimethylsiloxane (PDMS) substrate," Applied Physics Letters, 2014.

We investigate the strategies to improve the longevity and stability of polymer-based implants in physiological environments. In many cases, wireless power supply is favorable for implanted devices to eliminate the use of batteries in the body. Thus, we investigate short-range, low-power wireless powering for implantable devices. Also, we investigate the interactions between implants and the body, such as artificial discs, using finite element method.

Related publications

1. "Finite element analysis of a ball-and-socket artificial disc design to restrict torsional motion: a comparative study with ProDisc," International Journal for Numerical Methods in Biomedical Engineering, 2019.

2. "Biomechanical effects of the geometry of ball-and-socket artificial disc on lumbar spine: A finite element study," SPINE, 2017.

3. "Long-term characterization of neural electrodes based on parylene-caulked polydimethylsiloxane substrate," Biomedical Microdevices, 2016.

4. "Biomechanical comparison of spinal fusion methods using interspinous process compressor and pedicle screw fixation system based on finite element method," J. Korean Neurosurgical Society, 2016.

5. "Evaluation of Sub-micrometer Parylene C films as Passivation Layer Using Electrochemical Impedance Spectroscopy," Progress in Organic Coatings, 2014.

6. "Comparison of planar type coils for efficient power supply to implantable devices," Biomedical Engineering Letters, 2012.

7. "Influence of system integration and packaging on its inductive power link for a wireless neural interface device," IEEE Trans. on Biomedical Engineering, 2009.

8. "Integrated Wireless Neural Interface Based on the Utah Electrode Array," Biomedical Microdevices, 2009.

9. "Thermal impact of an active 3-D microelectrode array implanted in the brain," IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2007.

10. "Switchable polymer based thin film coils as a power module for wireless neural interfaces," Sensors and Actuators A, 2007.