In this work, the thermoelectric (TE) properties of poly(3,4- ethylenedioxylthiophene):poly(styrene sulfonate) (PEDOT:PSS) thin films at room temperature are studied. Different methods have been applied for tuning the TE properties: 1st addition of polar solvent, dimethyl sulfoxide (DMSO), into the PEDOT:PSS solution; 2nd post-treatment of thin films with a mixture of DMSO and ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4). It is verified that DMSO post-treatment is more efficient than DMSO addition in improving the electrical conductivity with a trivial change in the Seebeck coefficient. The power factor is increased up to 30.1 W mK-2 for the film with DMSO post-treatment, while the optimized power factor by DMSO addition is 18.2 W mK-2. It is shown that both DMSO addition and post-treatment induce morphological changes: an interconnected network of elongated PEDOT grains is generated, leading to higher electrical conductivity. In contrast, for t hose films post-treated in the presence of EMIMBF4, an interconnected network of short and circular PEDOT grains with increased polaron density is created, resulting in the improvement in the Seebeck coefficient and a concomitant compromise in the electrical conductivity. An optimized power factor of 38.46 W mK -2 is achieved at 50 vol% of EMIMBF4, which is the highest reported so far for PEDOT:PSS thin films to our knowledge. Assuming a thermal conductivity of 0.17 W mK-1, the corresponding ZT is 0.068 at 300 K. These results demonstrate that post-treatment is a promising approach to enhance the TE properties of PEDOT:PSS thin films. Furthermore, ionic liquid, EMIMBF4, shows the potential for tuning the TE properties of PEDOT:PSS thin films via a more environmentally benign process

We report on the modification of the thermoelectric properties of poly(3,4-ethylenedioxylthiophene):poly(styrenesulfonate) (PEDOT:PSS) thin films by means of a simple post treatment of the solid thin films realized by drop-coating. We show that the organic polar solvents, dimethyl sulfoxide and ethylene glycol as secondary dopants for PEDOT:PSS, only affect the film morphology for which a high electrical conductivity is observed. In contrast, ethanolamine (MEA) and ammonia solutions are reduction agents that improve the density of PEDOT chains in the reduced forms (polaron and neutral states), resulting in the trade-off between Seebeck coefficient and electrical conductivity. Furthermore, we show that the nature of amines determines the reduction degree: the nitrogen lone pair electrons in MEA are easier to be donated than those in ammonia solution and will therefore neutralize the PEDOT chains

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A polymer-based sensor for low frequency acceleration detection is fabricated by using microinjection molding technologies. Finite Element simulations and characterization of the sensing functionality are done. Due to an out-of-plane acceleration a force is applied to a seismic mass (length and width each 3.2 mm, thickness 1 mm), which leads to a deformation of a connected plate with dimensions of 1 mm × 1 mm × 50 ?m. Thus, charge separation at the electrodes of integrated piezoelectric polyvinylidene fluoride (PVDF) copolymer sheets occur and can be measured as sensor signal. A charge sensitivity of 0.57 pC/g is determined which is in good agreement with the simulation results. A resonance frequency of 660 Hz was measured. Furthermore, the sensor concept as well as preparation technologies to assemble a compound structure containing piezoelectric layers and the system integration by micro injection molding are discussed. In addition, different bonding techniques for the assembly of the functional components are investigated and described

This paper describes the application of a new method to verify the pressure and sealing of cavities in micromechanical components. The new method makes it possible to measure the pressure and the sealing (through measuring the pressure over time) of smallest gasvolumes with the monitoring of the quality factor of integrated micromechanical resonant structures. An example is used that shows the complete process of fabricating such micro mechanical resonant structures to evaluate a bonded structure

This paper presents a MEMS fabrication technique for reducing the trench width of microstructures below the technological limitations of the deep reactive ion etching (DRIE) process, in order to increase the aspect ratio of the sensing electrode gap of capacitive transducers. The in-process trench width reduction is based on the displacement of a substructure actuated by a buckling beam mechanism. Compressive stress causes a longitudinal force in the acting beams which results in the buckling to a predefined direction. This way, the capacitive sensitivity and hence the signal to area ratio of a transverse comb structure could be increased by a factor of 5