title: Micromachined lab-on-a-tube sensors for simultaneous brain temperature and cerebral blood flow measurements.
abstract: This work describes the development of a micromachined lab-on-a-tube device for simultaneous measurement of brain temperature and regional cerebral blood flow. The device consists of two micromachined gold resistance temperature detectors with a 4-wire configuration. One is used as a temperature sensor and the other as a flow sensor. The temperature sensor operates with AC excitation current of 500 μA and updates its outputs at a rate of 5 Hz. The flow sensor employs a periodic heating and cooling technique under constant-temperature mode and updates its outputs at a rate of 0.1 Hz. The temperature sensor is also used to compensate for temperature changes during the heating period of the flow sensor to improve the accuracy of flow measurements. To prevent thermal and electronic crosstalk between the sensors, the temperature sensor is located outside the "thermal influence" region of the flow sensor and the sensors are separated into two different layers with a thin-film Copper shield. We evaluated the sensors for accuracy, crosstalk and long-term drift in human blood-stained cerebrospinal fluid. These in vitro experiments showed that simultaneous temperature and flow measurements with a single lab-on-a-tube device are accurate and reliable over the course of 5 days. It has a resolution of 0.013 °C and 0.18 ml/100 g/min; and achieves an accuracy of 0.1 °C and 5 ml/100 g/min for temperature and flow sensors respectively. The prototype device and techniques developed here establish a foundation for a multi-sensor lab-on-a-tube, enabling versatile multimodality monitoring applications.
authors.affiliation: Cushing Neuromonitoring Laboratory, Feinstein Institute for Medical Research, North Shore Long Island Jewish Health System, Manhasset, NY 11030, USA. cli11@nshs.edu
authors.forename: Chunyan
authors.initials: C
authors.lastname: Li
authors.forename: Pei-Ming
authors.initials: PM
authors.lastname: Wu
authors.forename: Jed A
authors.initials: JA
authors.lastname: Hartings
authors.forename: Zhizhen
authors.initials: Z
authors.lastname: Wu
authors.forename: Cletus
authors.initials: C
authors.lastname: Cheyuo
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.forename: David
authors.initials: D
authors.lastname: LeDoux
authors.forename: Lori A
authors.initials: LA
authors.lastname: Shutter
authors.forename: Bharat Ram
authors.initials: BR
authors.lastname: Ramaswamy
authors.forename: Chong H
authors.initials: CH
authors.lastname: Ahn
authors.forename: Raj K
authors.initials: RK
authors.lastname: Narayan
mesh_terms: D001921:Brain / Q000098:blood supply*; D002560:Cerebrovascular Circulation; D055616:Microtechnology / Q000295:instrumentation*; D013696:Temperature; D013997:Time Factors