Generic Fabrication Technique of Graphene Based RF Sensor towards Biological Application

Herein presented, we demonstrate that a sensitive sensing/detection element was obtained from the laser treatment of a non-conducting flexible material exploiting laser machine, which can then potentially deploy as sensing element of a biosensor for possible usage in to sense and obtain the presence and quantity of the interested sample. The goal is to study and advance innovative means of fabricating a low-cost graphene sensor, employed as a Radio Frequency (RF) filter for disposable biomedical purposes. A material like Graphene can be fashioned by laser irradiation (Laser scribe) of Kapton tape implemented as a filter. The manufacture of the filter geometry was accomplished by means of a laser machine irradiating a Kapton tape on a chosen substrate (for this work a Flame Retardant 4 (FR-4)), by the application of the previous gotten parameters for the production. Various laser power values were employed for their manufacture and their corresponding conductivity was observed to range from 171 x10-6 S/mm to 279 x10-6 S/mm. The Raman spectrum results of the produced material has a D band peak at 1349.76 cm-1 , a G band of 1587.73 cm-1 and a 2D band peak of 2693.34 cm-1 . The ANSYS high-frequency structure simulator (HFSS) (for the Analysis of the System) simulation results signifies good outcomes, and opportunities to improve the material property are also being studied. Tests were also conducted by the utilization of a Vector Network Analyzer (VNA) to validating their feasibility of being deployed as the detection element of a biosensor, thus lending them the possibility to find implementation in disposable biological sensing.

A Highly-efficient, Stable and Flexible Kapton Tape-based SERS Chip

A flexible SERS chip fully covered with silver (Ag) nanoparticles is obtained by one-step metal thermal deposition on the Kapton tape, exhibiting ultrasensitivity, high-uniformity, and especially long-term SERS stability up...

Acquisition and Analysis of Hyperspectral Thermal Images for Sample Segregation

This study presents the first results of a new type of hyperspectral imager in the long-wave thermal radiation range from 8.0 to 14.0 µm which is simpler than readily available Fourier transform infrared spectroscopy-based imagers. Conventional thermography images the thermal radiation from hot objects, but an accurate determination of temperature is hampered by the often unknown emissivities of different materials present in the same image. This paper describes the setup and development of a hyperspectral thermal camera based on a low-order scanning Fabry–Pérot interferometer acting as a bandpass filter. A three-dimensional hyperspectral data cube (two spatial and one spectral dimension) was measured by imaging a high-emissivity carbon nanotube-coated surface (Vantablack), black painted aluminum, borosilicate glass, Kapton tape, and bare aluminum. A principal component analysis (PCA) of the hyperspectral thermal image clearly segregates the individual samples. The most distinguishable sample from the PCA is the borosilicate Petri dish of which the Si–O–Si bond in borosilicate glass was the most noticeable. Additionally, it was found that the relatively large 1024 × 768 × 70 data cube can be reduced to a much smaller cube of size 1024 × 768 × 5 containing 92% of the variance in the original dataset. The possibility of discriminating between the samples by their spectroscopic signature was tested using a logistic regression classifier. The model was fitted to a chosen set of principal components obtained from a PCA of the original hyperspectral data cube. The model was used to predict all pixels in the original data cube resulting in estimates with very high true positive rate (TPR). The highest TPR was obtained for borosilicate glass with a value of 99% correctly predicted pixels. The remaining TPRs were 94% for black painted aluminum, 81% for bare aluminum, 79% for Kapton tape, and 70% for Vantablack. A standard thermographic image was acquired of the same objects where it was found that the samples were mutually indistinguishable in this image. This shows that the hyperspectral thermal image contains sample characteristics which are material related and therefore outperforms standard thermography in the amount of information contained in an image.

Photolithographically Home-Made PVDF Sensor for Cavitation Impact Load Measurement

Piezoelectric PVDF sensors offer a unique option for the measurement of cavitation aggressiveness represented by the magnitude of impacts due to cavitation bubble collapses near walls. The aggressiveness measurement requires specific sensors shape and area, whereas commercial PVDF sensors are fabricated in limited geometry and size ranges. The photolithography method offers a possibility of production of home-made PVDF sensors of arbitrary shape and size. This paper deals with the calibration of a photolithographically home-made PVDF sensor for the cavitation impact load measurement. The calibration of sensors was carried out by the ball drop method. Sensors of different sizes were fabricated by the photolithography method from multi-purpose both side metallized PVDF sheet. The standard technology used for the fabrication of printed circuit boards was utilized. Commercial PVDF sensors of the same size were calibrated and the calibration results were compared with the home-made sensors. The effect of size and the effect of one added protective layer of Kapton tape on a sensor sensitivity were investigated.

Power electronics thermal solutions using thermally conductive polyimide films

Increased adoption of hybrid and electrical vehicles as well as renewable energy systems are driving the innovation in power module packaging. Thermal substrate, one of the major components of power modules, is not an exception, and technological advancements are necessary to meet increased reliability requirements. DuPont has developed a thermally conductive polymer film that provides very low thermal resistance and very high insulation. The film can be bonded to conductive and thick metallic layers and this polymer equivalent of DBC shows very high reliability in addition to high performance characteristics. Electrically insulating layers within a power electronics module are critical for separating circuitry from thermal management layers. Electrical insulating substrates typically used in power electronics modules utilize a ceramic layer, comprised most commonly of either Al2O3, AlN, or Si3N4. Thin Cu layers are bonded to either side of the substrate using a direct bond Cu (DBC) or active metal brazing (AMB) process. These processes involve bonding metallization layers to both sides of the ceramic at a high temperature as bonding to only one side would cause deformation during the cooling phase. Typical metal thickness bonded to either side of the ceramic is about 0.3–0.6 mm as the high temperature manufacturing process does not allow very thick metals to be bonded and this limits the heat spreading capability of the thermal substrate. DuPont's new Temprion™ Organic Direct Bond Copper (ODBC) address aforementioned problems, increasing thermal durability and reliability as well as enabling system layer suppression. Temprion™ ODBC's dielectric layer will absorb thermo-mechanical stress from the metals due to CTE mismatch, dramatically improving durability of the system. In addition, various kinds of metals including Cu and Al can be easily bonded to Temprion™ DB films through simple process. There are no thickness limitations on bonding metal sheets and metal attached at the bottom can be used as an integrated heat sink/baseplate. Al2O3 and Si3N4-based substrates were utilized as a baseline for reliability comparison with the DuPont substrates. The industry-standard substrates in used in this study have a thickness of 0.3 and 0.8 mm for the Cu metallization layers and 0.38 and 0.32 mm for the insulating layer respectively for Al2O3 an Si3N4 insulators. DuPont ODBC substrates were fabricated by attaching a polyimide layer to a layer of 0.8-mm-thick Cu. The polyimide and bottom Cu layer cross-sectional footprints are both 50.8 mm × 50.8 mm. The corners of both layers were filleted with various radii (0.5, 1.0, 2.0, and reversed 2.0 mm) to explore the impact of different stress concentrations between the metallization and insulating layers. The top Cu metallization was inset 2.0 mm from the perimeter of the electrically-insulating substrate and bottom Cu metallization.10 samples each of the DuPont ODBC and industry Al2O3 substrates were placed in a thermal shock chamber and cycled between temperature extremes of −40°C and 200°C. Substrates were inspected every 1000 cycles. After 5000 cycles, the ODBC substrates experienced no hipot failures, but preliminary edge delamination was visually observed. Al2O3 substrates all failed after 50 thermal cycles.Five DuPont ODBC samples were placed in a thermal chamber and subjected to an elevated temperature of 175°C. After 2000 hours, no hipot failures were observed, but edge delamination was again observed.Five DuPont ODBC samples were attached to a cold plate with Kapton tape. Heater cartridges were attached to the top of the substrates with Kapton tape and thermocouples were placed in several locations through the package. The heater cartridges were alternated between on and off states to allow for the substrates to cycle between −40°C and +200°C. While the change between the maximum and minimum temperatures is smaller for the power cycling test compared to the thermal cycling test, the heater cartridge and cold plate create a thermal gradient within the samples that is not possible with passive thermal cycling. After 2000 hrs cycles of testing, no hipot failures or edge delamination have been observed. Herein we show that the DuPont ODBC substrate design is a promising alternative to traditional industry substrates based on ceramic insulators. The reliability of the substrate design has been demonstrated under several thermomechanical accelerated tests and the electrical and thermal performance has been measured. Future work will include reliability comparisons to other industry substrates, including thermal shock testing of substrates with HPS, AlN, and Si3N4 ceramic layers. Thermal models will correlate thermal resistance values measured by the transient thermal tester and compare the ODBC substrate performance to industry substrates within a commercialized power electronics module. The modeling will also optimize the thickness of the metallization layers within the ODBC substrates to minimize the junction temperature of the switching devices.