A Flexible Vanadium Oxide Thermistor Array for Localized Temperature Field Measurements in Brain

Billard, Myles W.; Basantani, Hitesh A.; Horn, Mark W.; Gluckman, Bruce J.

doi:10.1109/jsen.2016.2517161

Cited by 11 publications

(10 citation statements)

References 9 publications

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“…It can be seen that relation (15), which is used for the calculation of temperature with the B equation approach, is merely a simplification of (17) if the cubic part is neglected (c = 0) and a and b are calculated from relation (6). For practical implementation in the microcontroller, the procedure for temperature calculation following (17) is not overly complex, after all, provided that the Steinhart-Hart parameters are known.…”

Section: Analytical Approach Using the Steinhart-hart Equationmentioning

confidence: 99%

“…Voltage and current measurements in electronic devices together with inventive circuit topologies can prevent severe malfunction, resulting in fault-tolerant devices that can still operate under a shortor open-circuit switch failure [2][3][4]. The case is similar regarding temperature measurements: they are not limited only to applications where the temperature of a technological process is monitored or controlled, as, for instance, in material science and mechanics [5], bioelectrochemistry and biomedical engineering [6,7] or microfluidics [8,9], to name just a few. Temperature measurements are also used-often in conjunction with voltage and current measurements-to monitor key components of the device in order to increase the operational safety and reliability of the device in general.…”

Section: Introductionmentioning

confidence: 99%

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Algorithm Execution Time and Accuracy of NTC Thermistor-Based Temperature Measurements in Time-Critical Applications

2021

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This paper addresses the challenges of selecting a suitable method for negative temperature coefficient (NTC) thermistor-based temperature measurement in electronic devices. Although measurement accuracy is of great importance, the temperature calculation time represents an even greater challenge since it is inherently constrained by the control algorithm executed in the microcontroller (MCU). Firstly, a simple signal conditioning circuit with the NTC thermistor is introduced, resulting in a temperature-dependent voltage UT being connected to the MCU’s analog input. Next, a simulation-based approximation of the actual temperature vs. voltage curve is derived, resulting in four temperature notations: for a look-up table principle, polynomial approximation, B equation and Steinhart–Hart equation. Within the simulation results, the expected temperature error of individual methods is calculated, whereas in the experimental part, performed on a DC/DC converter prototype, required prework and available MCU resources are evaluated. In terms of expected accuracy, the look-up table and the Steinhart–Hart equation offer superior results over the polynomial approximation and B equation, especially in the nominal temperature range of the NTC thermistor. However, in terms of required prework, the look-up table is inferior compared to the Steinhart–Hart equation, despite the latter having far more complex mathematical functions, affecting the overall MCU algorithm execution time significantly.

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Section: Analytical Approach Using the Steinhart-hart Equationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Algorithm Execution Time and Accuracy of NTC Thermistor-Based Temperature Measurements in Time-Critical Applications

2021

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“…Thermocouples and RTD's typically have low sensitivity (at +0.1% change in resistance per°C), making NTC based sensors the preferred choice in industry for their high accuracy (−4% change in resistance per°C) and stability [4][5][6]. Molding these rigid sensors onto flexible substrates is a challenge [7][8][9]6], and a large number of alternative methods for measuring temperature have been suggested, yet poor stability has continued to limit their use [10][11][12][13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Effect of particle contact on the electrical performance of NTC-epoxy composite thermistors

Deutz

Zwaag

Groen

2020

Mater. Res. Express

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As demand rises for flexible electronics, traditionally prepared sintered ceramic sensors must be transformed into fully new sensor materials that can bend and flex in use and integration. Negative temperature coefficient of resistance (NTC) ceramic thermistors are preferred temperature sensors for their high accuracy and excellent stability, yet their high stiffness and high temperature fabrication process limits their use in flexible electronics. Here, a low stiffness thermistor based on NTC ceramic particles of micron size embedded in an epoxy polymer matrix is reported. The effect of particle-to-particle contact on electrical performance is studied by arranging the NTC particles in the composite films in one of three ways: (1) Low particle contact, (2) Improved particle contact perpendicular to the electrodes and (3) dispersing high particle contact agglomerated clumps throughout the polymer. At 50 vol.% of agglomerated NTC particles, the composite films exhibit a β-value of 2069 K and a resistivity, ρ, of 3.3 · 10 5 Ωm, 4 orders of magnitude lower than a randomly dispersed composite at identical volume. A quantitative analysis shows that attaining a predominantly parallel connectivity of the NTC particles and polymer is a key parameter in determining the electrical performance of the composite film.

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“…An RTD is a temperature sensor that operates on the measurement principle that a material’s electrical resistance changes with temperature. RTDs have been used to add functionality in biodevices for blood flow [ 19 ], heart [ 20 ], and superficial [ 21 ] and deep [ 22 , 23 , 24 , 25 ] brain measurement applications. For high-performance thermal sensing coupled to an optrode, the proposed thermal sensor needs to meet the following main requirements: (1) Micrometer-size dimensions, so it can be integrated in the probe body.…”

Section: Introductionmentioning

confidence: 99%

LED Optrode with Integrated Temperature Sensing for Optogenetics

et al. 2018

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In optogenetic studies, the brain is exposed to high-power light sources and inadequate power density or exposure time can cause cell damage from overheating (typically temperature increasing of 2 ∘C). In order to overcome overheating issues in optogenetics, this paper presents a neural tool capable of assessing tissue temperature over time, combined with the capability of electrical recording and optical stimulation. A silicon-based 8 mm long probe was manufactured to reach deep neural structures. The final proof-of-concept device comprises a double-sided function: on one side, an optrode with LED-based stimulation and platinum (Pt) recording points; and, on the opposite side, a Pt-based thin-film thermoresistance (RTD) for temperature assessing in the photostimulation site surroundings. Pt thin-films for tissue interface were chosen due to its biocompatibility and thermal linearity. A single-shaft probe is demonstrated for integration in a 3D probe array. A 3D probe array will reduce the distance between the thermal sensor and the heating source. Results show good recording and optical features, with average impedance magnitude of 371 kΩ, at 1 kHz, and optical power of 1.2 mW·mm−2 (at 470 nm), respectively. The manufactured RTD showed resolution of 0.2 ∘C at 37 ∘C (normal body temperature). Overall, the results show a device capable of meeting the requirements of a neural interface for recording/stimulating of neural activity and monitoring temperature profile of the photostimulation site surroundings, which suggests a promising tool for neuroscience research filed.

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A Flexible Vanadium Oxide Thermistor Array for Localized Temperature Field Measurements in Brain

Cited by 11 publications

References 9 publications

Algorithm Execution Time and Accuracy of NTC Thermistor-Based Temperature Measurements in Time-Critical Applications

Algorithm Execution Time and Accuracy of NTC Thermistor-Based Temperature Measurements in Time-Critical Applications

Effect of particle contact on the electrical performance of NTC-epoxy composite thermistors

LED Optrode with Integrated Temperature Sensing for Optogenetics

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