Dataset Information

Pyrolytic carbon resonators for micromechanical thermal analysis.

ABSTRACT: Thermal analysis is essential for the characterization of polymers and drugs. However, the currently established methods require a large amount of sample. Here, we present pyrolytic carbon resonators as promising tools for micromechanical thermal analysis (MTA) of nanograms of polymers. Doubly clamped pre-stressed beams with a resonance frequency of 233 ± 4 kHz and a quality factor (Q factor) of 800 ± 200 were fabricated. Optimization of the electrical conductivity of the pyrolytic carbon allowed us to explore resistive heating for integrated temperature control. MTA was achieved by monitoring the resonance frequency and quality factor of the carbon resonators with and without a deposited sample as a function of temperature. To prove the potential of pyrolytic carbon resonators as thermal analysis tools, the glass transition temperature (T _g) of semicrystalline poly(L-lactic acid) (PLLA) and the melting temperature (T _m) of poly(caprolactone) (PCL) were determined. The results show that the T _g of PLLA and T _m of PCL are 61.0 ± 0.8 °C and 60.0 ± 1.0 °C, respectively, which are in excellent agreement with the values measured by differential scanning calorimetry (DSC).

SUBMITTER: Nguyen LQ

PROVIDER: S-EPMC6803650 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Pyrolytic carbon resonators for micromechanical thermal analysis.

Nguyen Long Quang LQ Larsen Peter Emil PE Larsen Tom T Goswami Sanjukta Bose SB Villanueva Luis Guillermo LG Boisen Anja A Keller Stephan Sylvest SS

Microsystems & nanoengineering 20191021

Thermal analysis is essential for the characterization of polymers and drugs. However, the currently established methods require a large amount of sample. Here, we present pyrolytic carbon resonators as promising tools for micromechanical thermal analysis (MTA) of nanograms of polymers. Doubly clamped pre-stressed beams with a resonance frequency of 233 ± 4 kHz and a quality factor (Q factor) of 800 ± 200 were fabricated. Optimization of the electrical conductivity of the pyrolytic carbon allowe ...[more]

PMID: 31646000

Similar Datasets

Project description:Retinal prosthesis has been one of the medical strategies aimed at restoring some degree of vision for patients affected by retinal degenerative diseases, such as Retinitis Pigmentosa (RP) and age-related macular degeneration (AMD), which are leading causes of irreversible visual loss. In retinal prosthesis, electrical pulses are typically delivered to the retinal neurons via electrodes on the surface of the implant. In this work, we fabricated 3D carbon pillar electrodes by pyrolysis of SU-8 structures defined photolithographically on Si wafers. We then measured compound action potentials induced in porcine neuroretinas stimulated with electrical pulses. The recorded spikes were validated to be biological in origin by adding the voltage-gated sodium-channel blocking agent tetrodotoxin. The minimum threshold voltage needed to effectively stimulate retinal cells, such as retinal ganglion cells, with 3D electrodes was analyzed through systematic investigation of the spike rate and amplitudes as a function of stimulation voltage. 3D electrodes significantly increased spike rate and amplitudes above spontaneous activity in the tissue during stimulation and outperformed the 2D counterpart, both in terms of spike rate and amplitude. Our results indicate a threshold voltage range of 500-600 mV for 1 ms pulses at a frequency of 10 Hz above which a significant increase in spike count was observed. Furthermore, we report an order of magnitude increase in peak-to-peak amplitude for evoked spikes (> 3 mV), compared to spontaneous spikes (∼ 200 µV). Based on numerical integration, we estimate the area under the curve to be ~14 times larger in evoked compound action potentials compared to spontaneous activity. This indicates the relative increase in number of contributing cells to the compound action potential. At a stimulation voltage of 600 mV the spike rate for 3D electrodes was above 10 spikes/channel/s. We hypothesize that the significant difference between 2D and 3D electrodes is not only caused by the higher active electrode surface area of the 3D micropillar electrodes, but also by more intricate contact and interaction with the inner cell layers of the retinal tissue. Our findings indicate that 3D carbon micropillar electrodes are promising for electrical stimulation of the retina.

Dataset Information

Pyrolytic carbon resonators for micromechanical thermal analysis.

Publications

Pyrolytic carbon resonators for micromechanical thermal analysis.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets