Neural and Physiology Research
Neural and Physiology Research
Raman spectroscopy plays a key part in SSIM’s research into neural systems and physiology, including a bioreactor for growing neurons for use in biomachinery and for neurological research. SSIM’s expertise in nanoscale engineering is being used to develop sensors, integrated into helmets, for detecting hydration levels and traumatic brain injury in soldiers, footballers, hockey players, and others, and for creating chips to restore vision to the blind.
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We have developed a fractal-based bioreactor system for 3-D neuronal growth. Currently we are investigating a proof of concept that relies on electrical input and output for the stimulus and “behavior”. The capability to monitor the activity of neurons while processing a signal from input to output will add insight into the plasticity of the brain.
Future iterations of this device could incorporate cell populations that respond to stimulus such as light, vibration, chemotaxis, temperature, or pressure. These cell populations could be separated from the neural network with semipermeable membranes that allow neurotransmitters to begin the signaling cascade. Likewise, the output signal could be funneled to cultures of motor neurons that once stimulated could move a small device.
This system could be tested to determine if a small population of neurons could be trained with through stimulus and response. In addition, multiple devices could be combined and separated by a semipermeable membrane to gain insight into how white matter tracks passing orthogonally to each other can influence signal dynamics of passing signals.
The algorithms developed with this model will provide a look into a neuronal network based on real time stimulus and output of a collection of neurons arranged to deliver a singular output. In addition, the algorithms could be enveloped into research in brain/machine interface, particularly surface EMG electrodes that do not penetrate the brain and therefor do not have as strong a signal as penetrating electrodes, as well as neural prosthetics whose electrodes penetrate the brain, but lose the signal over time due to the stiffness and biocompatibility of current electrodes.
Helmet Integrated Neurospinal Hydration Sensor
The NSHS program goal is to design and integrate an ultra-thin, flexible electronics based, low cost, stretchable sensor system for precision passive measurement of both levels of human hydration and force-induced body injury.
Hydration is a critical nutrient for optimal functioning of the human body. Water balance is precisely regulated within the body as even a 1-2% decrease in water deficit produces impaired cognitive performance decrements. Dehydration is a major factor in heat stress morbidity and is a contributor to accidents and injuries through degraded neurological and muscle performance. Therefore the hydration state of an individual’s involved military training and military combat missions is of extreme importance across the spectrum of security personnel, combat soldiers, vehicle crews, rotary wing aircrews and fixed wing aircrews.
Hydration regulation is also of importance in sports performance and labor intensive occupations, where exercise-induced exhaustion and labor-induced exhaustion occurs across all ambient temperature ranges, effecting neurological cognitive performance and muscle performance loss.
Brain and spine trauma represent a growing concern to both the Military and Sports participants. Force-induced body injury of the head and spine range from mild concussions, to severe traumatic brain injury, to death. Adverse forces on the head/neck/spine induce injuries ranging from dislocations, damaged/crushed vertebrae, to death. Blast induced forces to the head and neck have different damage mechanisms to the brain and spine due to overpressure time constants than impact blows from sports activities. Therefore, the identification and declaration of brain and spine injury requires different calibrated injury models for Military-use and Sports-use.
The SSIM-developed NSHS construct provides seminal advancement in three key areas in the application of wearable technologies to Military-use and Sports-use applications.
First, the program provides for a multi-modal integration of human performance data into one sensor by the real time collection of and maintaining awareness of both the individuals hydration status and the neurospinal environment. These data are critical in the monitoring military member short term and long term human medical status for performance of current and future military missions.
Second, by using printed flexible electronics technology, the program demonstrates the size, weight and power (SWAP) needs for integration of the NSHS into helmets and uniforms.
Third, the SWAP advantages of the printed flexible electronics technology sensors does not adversely impede upon important human factors elements in Military or Sports environments, therefore achieving performance advantage over the previous generations of heavier helmet shock/blast detection sensors.
As part of this initiative, we have developed an integrated helmet sensor system that translates impact to the helmet to brain impact, using a multiphysics brain model based on shear forces that translate to axon stretching. 4D ultrasound of brain density and structural information provides the mechanical model for the strain calculations.
Funded by US Air Force.
CNS and Retina Implant Technology
New research on a light activated caged Glutamate based retina stimulating implant is under development. The micropore implant chip is designed to deliver Glutamate spatially over the retina in proportion to light location and intensity. In addition, new advances in our flexible microelectrode arrays that provide stimulation to discrete populations of neurons and provide real-time feedback will be reviewed. These arrays are tailored to fit the geometry of the implant site and functionality desired. We have encapsulated the arrays in semiconductor biocompatible materials and selectively coat the system using biologically inert organic materials.
For the development and long-term effectiveness of implantable prosthesis, an in vitro investigation of neural cell interactions with the implant surface is extremely important. To enhance the performance of the prosthesis we have optimized neural electrode interactions by increasing biocompatibility and minimizing the growth of scar tissue mediated by glial cells for all surfaces we use for constructing the microelectrode arrays.
This central nervous system electrode array is integrated with wireless power and communication linked by high frequency magnetic field transmission. We have determined biocompatibility of the microelectrode array through in vitro and in vivo investigations using cultured rat cortical cells grown on the device and direct cortical implants in the rat brain. Through these in vitro and in vivo studies we have established the impedance response of the neurons to the device. This work is performed in collaboration with Henry Ford Health Systems Detroit Institute of Ophthalmology.
Flexible Penetrating Microelectrode Arrays
Smart Sensors and Integrated Microsystems (SSIM) Program
Wayne State University
College of Engineering Room 3172
5050 Anthony Wayne Drive
Detroit, MI 48202