A Novel Intracranial Pressure Readout Circuit for Passive Wireless LC Sensor

Abstract

We present a wide frequency range, low cost, wireless intracranial pressure monitoring system, which includes an implantable passive sensor and an external reader. The passive sensor consists of two spiral coils and transduces the pressure change to a resonant frequency shift. The external portable reader reads out the sensor's resonant frequency over a wide frequency range (35 MHz-2.7 GHz). We propose a novel circuit topology, which tracks the system's impedance and phase change at a high frequency with low-cost components. This circuit is very simple and reliable. A prototype has been developed, and measurement results demonstrate that the device achieves a suitable measurement distance (>2 cm), sufficient sample frequency (>6 Hz), fine resolution, and good measurement accuracy for medical practice. Responsivity of this prototype is 0.92 MHz/mmHg and resolution is 0.028 mmHg. COMSOL specific absorption rate simulation proves that this system is safe. Considerations to improve the device performance have been discussed, which include the size of antenna, the power radiation, the Analog-to-digital converter (ADC) choice, and the signal processing algorithm.

Progress in the Field of Micro-Electrocorticography

“…The use and utility of µECoG is clearly ascending, as its core and supporting technologies are being refined and new applications are being imagined. Next-generation technologies could be catalyzed by the development of μECoG devices that are fully untethered from the external world and include all of the necessary electronics (i.e., data acquisition, power transmission, and communication) directly on the device [124,125,126,127]. Such developments will enable integrated neuroprosthetic and neuromodulation systems that will have the ability to function for the lifetime of the patient.…”

Spiral planar coil design for the intracranial pressure sensor

“…It is demonstrated that the sensor could sense the pressure change by resonant frequency shift, as shown in Figure 12. There is a trade-off between frequency resolution and measurement time consumption (Babu & George, 2018;Wang et al, 2017). Our homemade reader spends 165 μS for one increment of frequency.…”

Systematic Design and HRV Analysis of a Portable ECG System Using Arduino and LabVIEW for Biomedical Engineering Training

“…The bandwidth was set to 0.05 to 150 Hz with an anti-aliasing filter of greater than -100 dB/decade for the low-pass filter [5]. The range of frequency for measurement of this physiological measurement is at low frequency in contrast to some other physiological circuitry application which can be in high frequencies [6]- [8]. The portable ECG was constructed as a daughter board for the Arduino Uno microcontroller, which was programmed to sample the signal at 750 Hz [9].…”

“…The firmware code is implemented on a microcontroller. The Arduino Uno R3 was selected for this project due to its availability, wide community support and its efficiency in high-speed prototyping [6]. Fig.…”