Biomedical Sensors and Subsystems

Print or save page as PDF
A Near Infrared Opto-mechanical Intracranial Pressure
Mostafa Ghannad-Rezaie and Nikos Chronis
(A) The near infrared pressure sensing technology. The external optical readout unit is used to collect spectroscopic data from the implanted the sensor in the near infrared (NI). (B) Cross sectional view (C) The working principle of the ICP sensor. (D) The microfabricated device sitting on a penny.
(A) The near infrared pressure sensing technology. The external optical readout unit is used to collect spectroscopic data from the implanted the sensor in the near infrared (NI). (B) Cross sectional view (C) The working principle of the ICP sensor. (D) The microfabricated device sitting on a penny.

Intracranial pressure (ICP) monitoring is widely used to evaluate therapeutic interventions in patients with severe traumatic brain injuries (TBIs), hydrocephalus and other ICP-elevated disorders. These condition required frequent ICP measurement and brain imaging, usually MRI.

We present a new family of implantable, wireless, MRI compatible and power-free optical microsensors that can potentially be used to accurately monitor intracranial pressure (ICP) over long periods of time. These microsensors vertically integrate a glass mini-lens with a two wavelengths quantum dot micropillar that is photolithographically patterned on an ICP-exposed silicon nitride membrane. The operation principle is based on a novel opto-mechanical transduction scheme that converts ICP changes into changes in the intensity ratio of the two wavelengths, near infrared fluorescent light emitted from the quantum dots. These microsensors are microfabricated using silicon bulk micromachining and they operate at an ICP clinically relevant pressure dynamic range (0-40mmHg).

We believe that the proposed microsensors will open up a new direction not only in ICP monitoring but in other pressure-related biomedical applications.

Updated 06/16/2011