While attending the MEMS & Sensors Executive Congress 2016 (MSEC2016), I met two very bright and capable young men, Nicholas Fritz and Jonathan Garich, from the Blain-Christen Lab at Arizona State University (ASU), School of Electrical, Computer and Energy Engineering (ECEE). These young research engineers are working with Dr. Jennifer Blain Christen, Assistant Professor and who also the Principal Investigator (PI) working with this team.
The project to which I was introduced is in its early phases, but it intrigued me as these two young engineers excitedly discussed their initial findings.
The MSEC2016 collaborated with ASU this year with a Sensors & Machine Learning Workshop as well as having the research students display their posters at MSEC2016 regarding various MEMS and Sensor-related research projects. Figure 1 shows the poster that caught my eye.
The poster on display
Elevated intracranial pressure (ICP), that is, inside the skull, could be deadly if the pressure is not sensed and relieved quickly. This condition can lead to a shortage of oxygen and glucose to the rest of the body that is essential to healthy tissue life in the body. Presently most solutions that monitor ICP are quite invasive as well as inaccurate.
The team is working on a low-cost MEMS piezoresistive sensor that would be easily integrated into an electrocorticography (EC0G) system. An ECoG system takes recordings from the brain’s cerebral cortex monitoring local field potentials in the brain. These types of measurements and their analysis help scientists and doctors understand epilepsy so they might be able to detect seizure zones in the brain area that might lead to surgical treatment of the disease.
The problem is that standard ECoG electrodes and procedure can cause swelling, air or gas in the cranial cavity and foreign body problems—all leading to intracranial pressure. The sensor device that the team is developing can be integrated with ECoG electrodes. They are looking at a very low cost MEMS sensor that may be able to be one-time-use.
The electronics for the epidural ICP monitoring system consists of an instrumentation amplifier to amplify the signal. The voltage regulator is a 6V device that regulates the 9V power from a battery. The calibration factor that translates the sensed voltage into pressure is 0.030 mV/mmHg.
The sensor and electronics block diagram. (Image courtesy of Reference 1)
An experimental craniotomy procedure was performed on a rat. Intracranial pressure was successfully monitored and analyzed in a benchtop experiment and in an animal model using an epidural ICP monitoring system. The result showed the efficacy of the sensor for epidural ICP monitoring and demonstrated that the system was able to continuously measure ICP.
The basic diagram of the craniotomy electronics (Image courtesy of Reference 1)
Discrete components were used in the Reference 1 experiment and an integrated system design is the goal with a low cost sensor design that can be embedded into an ECoG electrode grid.
I am hoping to follow the progress of this study as it progresses since I live just across town from the University. More to come on this subject soon.
1 Design and Evaluation of a Low Cost Intracranial Pressure Monitoring System, Ranjani Sampath Kumaran, Bradly Greger and Jennifer Blain Christen, IEEE Xplore.
2 Design, Fabrication, and Testing of a Hybrid CMOS/PDMS Microsystem for Cell Culture and Incubation, Jennifer Blain Christen, Student Member, IEEE, and Andreas G. Andreou, Fellow, IEEE, IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS, VOL. 1, NO. 1, MARCH 2007