Sacrificial Volume Materials for Small Hole Generation in Low-Temperature Cofired Ceramics

The creation of hole, cavity or channel structures in low-temperature cofired ceramics (LTCCs), using different sacrificial volume materials (SVMs) was tested. The main functionality of the SVMs should be: easy application into the holes; protection of holes during lamination; uninhibited lamination between layers; and, during firing should burn out before the pores of the LTCCs close, to leave the empty holes clear of any residue. Five different materials were tested—hydroxyethyl cellulose (HEC) 2 wt%, HEC 5 wt%, agar-agar, gelatin, and commercial carbon paste—and compared to a reference sample where no SVMs were used. In all cases, lamination parameters were minimised in order to preserve the tested hole structures. Matrixes with holes ranging from 158 to 268 µm, with pitches of 573 µm in a green state, were tested. The agar-agar caused ceramic deformation as a result of thermal burst during firing and the lamination between the layers was compromised. The carbon paste was difficult to handle, requiring extra equipment for hole filling and incomplete filling of the larger holes. Traces of carbon paste were left as a landing pad on top of the holes, inhibiting lamination at these areas. The gelatin and the 2 wt% and 5 wt% hydroxyethylcellulose (HEC 2 wt% and HEC 5 wt%) filled all holes completely, and also worked as adhesive-assisted lamination (AAL) materials with excellent lamination between layers. Excellent lamination was also observed in the no-SVM case. Thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) analyses established that, for all SVMs tested, the remaining residue is negligible after firing. As a result, the HEC 2 wt% material was considered ideal for use as an SVM.

Plasma Jets Fabricated in Low-Temperature Cofired Ceramics for Gold Nanoparticles Synthesis

In this article, we present a development of atmospheric pressure plasma jets (APPJs) for modification of liquid solutions. APPJs were fabricated in low temperature cofired ceramics (LTCC) technology. During the measurements, plasma jets worked under various flowing gases, which can be used to produce plasma activated water. In addition, owing to the plasma treatment, it was possible to decrease the time of a synthesis of gold nanoparticles (AuNPs) without the use of additional hazardous reagents. The mechanism of gold nanoparticles formation in cold nitrogen plasma is also presented.

Fluorescence Sensing Platforms for Epinephrine Detection Based on Low Temperature Cofired Ceramics

A novel fluorescence-sensing pathway for epinephrine (EP) detection was investigated. The ceramic-based miniature biosensor was developed through the immobilization of an enzyme (laccase, tyrosinase) on a polymer—poly-(2,6-di([2,2′-bithiophen]-5-yl)-4-(5-hexylthiophen-2-yl)pyridine), based on low temperature cofired ceramics technology (LTCC). The detection procedure was based on the oxidation of the substrate, i.e., in the presence of the enzyme. An alternative enzyme-free system utilized the formation of a colorful complex between Fe2+ ions and epinephrine molecules. With the optimized conditions, the analytical performance illustrated high sensitivity and selectivity in a broad linear range with a detection limit of 0.14–2.10 nM. Moreover, the strategy was successfully used for an EP injection test with labeled pharmacological samples.

Investigation of low-temperature cofired ceramics packages for high-temperature SAW sensors

Surface acoustic wave (SAW) temperature sensor devices have been developed for operating temperatures up to and above 1000 °C. A challenging task to make these devices available on the market is to develop an appropriate housing concept. A concept based on low-temperature cofired ceramics (LTCC) has been investigated and tested under elevated temperatures up to 600 °C. The devices showed promising results up to 450 °C. Thorough analysis of the possible failure mechanisms was done to increase the maximum temperature above this limit in further production cycles.