Efficient Excitation of Micro/Nano Resonators and Their Higher Order Modes

We demonstrate a simple and flexible technique to efficiently activate micro/nano-electromechanical systems (MEMS/NEMS) resonators at their fundamental and higher order vibration modes. The method is based on the utilization of the amplified voltage across an inductor, L, of an LC tank resonant circuit to actuate the MEMS/NEMS resonator. By matching the electrical and mechanical resonances, significant amplitude amplification is reported across the resonators terminals. We show experimentally amplitude amplification up to twelve times, which is demonstrated to efficiently excite several vibration modes of a microplate MEMS resonator and the fundamental mode of a NEMS resonator

Inkjet printing of thin film transistors

Currently, the fabrication of functional electronic elements by additive manufacturing (AM) is beneficial due to the minimum structural limitations required for this flexible process. As a result, products can be customised and produced to meet the requirements for specific applications, such as in the medical field and automotive industry. However, thus far, only a few varying electronic devices, such as resistors and capacitors, are manufactured by AM technology due to a limited range of processable materials and the insufficient understanding of the fabrication process. Therefore, to broaden the opportunities of printed electronics in academia and industry, it is imperative to investigate a wider range of useable materials and comprehensively understand the AM process. In this thesis, attention is focused on various aspects involved in the fabrication of thin-film transistors (TFTs) by inkjet printing technology, from ink development to product characterisation, and a comprehensive understanding of this process is provided. For this research, silver, polyimide, tripropylene glycol diacrylate (TPGDA) and graphene oxide inks are prepared and characterised. In addition, the interrelation between printing mechanisms, process parameters and sintering approaches of these inks is investigated. Printing performances revealed that stable printing processes are achieved for silver, PI and TPGDA inks; however, printed graphene-oxide flakes are located non-uniformly on the printed specimens due to the Marangoni effect. Graphene-based TFTs are partially and fully produced by inkjet printing technology. Electrical characterisation results indicate that partially printed graphene transistors on a silicon wafer exhibit good performance, while fully printed graphene transistors need to be modified due to their output performance. Apart from the investigation on printable inks and transistors, indium selenide (InSe) is examined by the inkjet printing of conductive electrodes on generated InSe flakes to form characterising elements such as Hall bar. The material, which exhibits photosensitive and semiconducting properties during characterisation, is expected to be developed into printable inks for the fabrication of printed semiconductor devices and optoelectronic applications. Significant achievements of inkjet printing for functional electronic applications are examined. Partially printed graphene TFTs are fabricated by a single process, and UV light is employed for the reduction of graphene oxide in inkjet-printed TFTs for the first time to the best of our knowledge. Meanwhile, InSe is also investigated in this thesis. All these findings provide opportunities for potential printed electronics in the future

Inkjet printing of thin film transistors

Currently, the fabrication of functional electronic elements by additive manufacturing (AM) is beneficial due to the minimum structural limitations required for this flexible process. As a result, products can be customised and produced to meet the requirements for specific applications, such as in the medical field and automotive industry. However, thus far, only a few varying electronic devices, such as resistors and capacitors, are manufactured by AM technology due to a limited range of processable materials and the insufficient understanding of the fabrication process. Therefore, to broaden the opportunities of printed electronics in academia and industry, it is imperative to investigate a wider range of useable materials and comprehensively understand the AM process. In this thesis, attention is focused on various aspects involved in the fabrication of thin-film transistors (TFTs) by inkjet printing technology, from ink development to product characterisation, and a comprehensive understanding of this process is provided. For this research, silver, polyimide, tripropylene glycol diacrylate (TPGDA) and graphene oxide inks are prepared and characterised. In addition, the interrelation between printing mechanisms, process parameters and sintering approaches of these inks is investigated. Printing performances revealed that stable printing processes are achieved for silver, PI and TPGDA inks; however, printed graphene-oxide flakes are located non-uniformly on the printed specimens due to the Marangoni effect. Graphene-based TFTs are partially and fully produced by inkjet printing technology. Electrical characterisation results indicate that partially printed graphene transistors on a silicon wafer exhibit good performance, while fully printed graphene transistors need to be modified due to their output performance. Apart from the investigation on printable inks and transistors, indium selenide (InSe) is examined by the inkjet printing of conductive electrodes on generated InSe flakes to form characterising elements such as Hall bar. The material, which exhibits photosensitive and semiconducting properties during characterisation, is expected to be developed into printable inks for the fabrication of printed semiconductor devices and optoelectronic applications. Significant achievements of inkjet printing for functional electronic applications are examined. Partially printed graphene TFTs are fabricated by a single process, and UV light is employed for the reduction of graphene oxide in inkjet-printed TFTs for the first time to the best of our knowledge. Meanwhile, InSe is also investigated in this thesis. All these findings provide opportunities for potential printed electronics in the future