Laboratory for Emerging Nanometrology LENA

Braunschweig, Germany

Laboratory for Emerging Nanometrology LENA

Braunschweig, Germany
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Hamdana G.,TU Braunschweig | Hamdana G.,Laboratory for Emerging Nanometrology LENA | Bertke M.,TU Braunschweig | Bertke M.,Laboratory for Emerging Nanometrology LENA | And 7 more authors.
Journal of Sensors and Sensor Systems | Year: 2017

A developed transferable micro force sensor was evaluated by comparing its response with an industrially manufactured device. In order to pre-identify sensor properties, three-dimensional (3-D) sensor models were simulated with a vertically applied force up to 1000μN. Then, controllable batch fabrication was performed by alternately utilizing inductively coupled plasma (ICP) reactive ion etching (RIE) and photolithography. The assessments of sensor performance were based on sensor linearity, stiffness and sensitivity. Analysis of the device properties revealed that combination of a modest stiffness value (i.e., (8.19±0.07)Nm'1) and high sensitivity (i.e., (15.34±0.14)VN'1) at different probing position can be realized using a meander-spring configuration. Furthermore, lower noise voltage is obtained using a double-layer silicon on insulator (DL-SOI) as basic material to ensure high reliability and an excellent performance of the sensor. © Author(s) 2017.

Schmidt I.,TU Braunschweig | Gad A.,TU Braunschweig | Gad A.,Laboratory for Emerging Nanometrology LENA | Gad A.,National Research Center of Egypt | And 13 more authors.
Biosensors and Bioelectronics | Year: 2017

Microbial electrochemical technologies (METs) are one of the emerging green bioenergy domains that are utilizing microorganisms for wastewater treatment or electrosynthesis. Real-time monitoring of bioprocess during operation is a prerequisite for understanding and further improving bioenergy harvesting. Optical methods are powerful tools for this, but require transparent, highly conductive and biocompatible electrodes. Whereas indium tin oxide (ITO) is a well-known transparent conductive oxide, it is a non-ideal platform for biofilm growth. Here, a straightforward approach of surface modification of ITO anodes with gold (Au) is demonstrated, to enhance direct microbial biofilm cultivation on their surface and to improve the produced current densities. The trade-off between the electrode transmittance (critical for the underlying integrated sensors) and the enhanced growth of biofilms (crucial for direct monitoring) is studied. Au-modified ITO electrodes show a faster and reproducible biofilm growth with three times higher maximum current densities and about 6.9 times thicker biofilms compared to their unmodified ITO counterparts. The electrochemical analysis confirms the enhanced performance and the reversibility of the ITO/Au electrodes. The catalytic effect of Au on the ITO surface seems to be the key factor of the observed performance improvement since the changes in the electrode conductivity and their surface wettability are relatively small and in the range of ITO. An integrated platform for the ITO/Au transparent electrode with light-emitting diodes was fabricated and its feasibility for optical biofilm thickness monitoring is demonstrated. Such transparent electrodes with embedded catalytic metals can serve as multifunctional windows for biofilm diagnostic microchips. © 2017 Elsevier B.V.

Xu J.,TU Braunschweig | Xu J.,Laboratory for Emerging Nanometrology LENA | Bertke M.,TU Braunschweig | Bertke M.,Laboratory for Emerging Nanometrology LENA | And 10 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2017

A ZnO nanorods film covered silicon resonant cantilever sensor is developed for atmosphere humidity detection by monitoring the resonant frequency shifts induced by the additional weight of adsorbed water molecules. Two different crystalline seed-layer deposition methods were applied to grow different nanorods films. The morphology of the ZnO films were characterized and the sensor sensitivities were measured under different relative humidity (RH) levels. The experiments results showed that this novel humidity sensor with ZnO nanorods has a sensitivity of 101.5 ± 12.0 ppm/RH% (amount of adsorbed water of 36.9 ± 4.4 ng/RH%), indicating its potential for portable sensing applications. © 2017 SPIE.

Hamdana G.,TU Braunschweig | Hamdana G.,Laboratory for Emerging Nanometrology LENA | Sudkamp T.,University of Munster | Descoins M.,CNRS Institute Materials Microelectronics nanosciences of Provence | And 9 more authors.
Microelectronic Engineering | Year: 2017

An improved nanofabrication processing technique for realization of vertically aligned silicon nanowires (SiNWs) by colloidal lithography is reported in this work. Microstructure pattern arrays are prepared on the substrate allowing selective deposition of polystyrene (PS) nanoparticles. Using PSS/PDDA/PSS-layer, surface properties can be modified resulting in an enhanced hydrophilicity of the silicon substrate, which is followed by high surface coverage up to ~ 83% after particle transfer. During the fabrication, we demonstrate full control of the mask dimension providing excellent control of nanostructure feature size by inductively coupled plasma (ICP) reactive ion etching (RIE) process at cryogenic temperature. Finally, this combined approach of bottom-up and top-down methods offers simple and direct nanoscale processing steps with low-cost and great reproducibility, enabling high density fabrication of nanostructure (~ 109 SiNW/cm2) within certain area. This preparation route of the SiNWs was applied to isotopically controlled silicon layers grown epitaxially on Si substrates. Atom probe tomography of these SiNWs reveal that the isotope layer ordering is preserved by the NW fabrication route. © 2017 Elsevier B.V.

Bertke M.,Hans Tech | Bertke M.,Laboratory for Emerging Nanometrology LENA | Hamdana G.,Hans Tech | Hamdana G.,Laboratory for Emerging Nanometrology LENA | And 7 more authors.
Journal of Physics: Conference Series | Year: 2016

The asymmetric resonance frequency analysis of silicon cantilevers for a low-cost wearable airborne nanoparticle detector (Cantor) is described in this paper. The cantilevers, which are operated in the fundamental in-plane resonance mode, are used as a mass-sensitive microbalance. They are manufactured out of bulk silicon, containing a full piezoresistive Wheatstone bridge and an integrated thermal heater for reading the measurement output signal and stimulating the in-plane excitation, respectively. To optimize the sensor performance, cantilevers with different cantilever geometries are designed, fabricated and characterized. Besides the resonance frequency, the quality factor (Q) of the resonance curve has a high influence concerning the sensor sensitivity. Because of an asymmetric resonance behaviour, a novel fitting function and method to extract the Q is created, different from that of the simple harmonic oscillator (SHO). For testing the sensor in a long-term frequency analysis, a phase- locked loop (PLL) circuit is employed, yielding a frequency stability of up to 0.753 Hz at an Allan variance of 3.77 10-6. This proposed asymmetric resonance frequency analysis method is expected to be further used in the process development of the next-generation Cantor. © Published under licence by IOP Publishing Ltd.

Wasisto H.S.,Hans Tech | Wasisto H.S.,Laboratory for Emerging Nanometrology LENA | Merzsch S.,Hans Tech | Uhde E.,Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut | And 4 more authors.
Microelectronic Engineering | Year: 2015

The development and real-time performance test of a fully integrated low-cost handheld cantilever-based airborne nanoparticle (NP) detector (CANTOR-2) are described in this paper. The device is the enhancement of the previously developed cylindrical electrophoretic NP sampler (CANTOR-1), which is used for direct-reading of exposure to airborne carbon engineered nanoparticles (ENPs) in indoor workplaces. All components of the proposed detector can be divided into two main units depending on their packaging placements (i.e., the NP sampler head and the electronics mounted in a handy-format housing). For the NP sampler, a miniaturized electrophoretic aerosol sampler created in a cubical shape and an electrothermal piezoresistive resonant silicon cantilever mass sensor are employed for collecting the ENPs from the air stream to the cantilever surfaces and measuring their mass concentration, respectively. To realize a real-time measurement, a frequency tracking system based on phase-locked loop (PLL) is built and integrated to the device. From the device calibration, a good correlation of the CANTOR-2 data is found with the fast mobility particle sizer (FMPS, TSI 3091) reference at a precision of 8-14%. By having a total device volume of 540 cm3, weight of 375 g, and power consumption of 1.25 W in the current version, this developed CANTOR-2 provides a very good portability for being used as a personal airborne NP monitoring device, which can be easily held or worn by workers during their activities. © 2015 Elsevier B.V. All rights reserved.

Wasisto H.S.,TU Braunschweig | Wasisto H.S.,Laboratory for Emerging Nanometrology LENA | Dang R.,TU Braunschweig | Doering L.,Physikalisch - Technische Bundesanstalt | And 3 more authors.
Procedia Engineering | Year: 2015

Silicon cantilever resonators fabricated in a slender geometry are investigated for detecting characteristics of local elasticity of different surface deposits by monitoring changes of resonance frequency and quality factor (Q-factor) corresponding to the physical properties of the materials. A full piezoresistive Wheatstone bridge (WB) for signal read-out and a wet-etched silicon tip for surface probing are integrated on the cantilever beam. From the material characterization, the harder the object surface, the larger the resonance frequency shift is while amplitude and Q-factor decrease. This sensor will be the key component of an adaptable form and roughness monitoring system for inline process control of machine tools for high-aspect-ratio microstructures. © 2015 The Authors. Published by Elsevier Ltd.

Wasisto H.S.,TU Braunschweig | Wasisto H.S.,Laboratory for Emerging Nanometrology LENA | Uhde E.,Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut | Peiner E.,TU Braunschweig | Peiner E.,Laboratory for Emerging Nanometrology LENA
Building and Environment | Year: 2016

An electrophoretic cantilever-based nanoparticle (NP) sensor was described and evaluated for personal monitoring of occupational exposure at indoor environment. Measurements performed under defined NP concentrations in a conditioned chamber confirmed the feasibility of the measurement principle. For the first laboratory sample of the sensor cyclic switching between NP sampling and frequency tracking revealed settling times of 5 min and 1.5 min, respectively, until stable conditions were reached. Using an enhanced design of the sampling head this response time was considerably reduced to 20 s. With a total device volume of 540 cm3, weight of 375 g, and power consumption of 1.25 W the fully integrated pocket-sized system can be easily held or worn, e. g., by workmen in nanotechnology industry during their working shifts. © 2015 Elsevier Ltd.

Wasisto H.S.,TU Braunschweig | Wasisto H.S.,Laboratory for Emerging Nanometrology LENA | Wu W.,TU Braunschweig | Wu W.,Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut | And 6 more authors.
2015 Transducers - 2015 18th International Conference on Solid-State Sensors, Actuators and Microsystems, TRANSDUCERS 2015 | Year: 2015

A low-cost pocket-sized airborne nanoparticle (NP) detector based on a silicon microelectromechanical cantilever is described oscillating at its fundamental in-plane resonance frequency. For direct reading of NP concentrations, the monitoring system consists of signal-conditioning electronics for NP sampling as well as tracking of frequency shift by the attached NP mass. Weight and cost of this first fully integrated personal gravimetric airborne NP monitor (Cantor-2) are comparable to low-cost optical fine-particle sensors but beyond this it can detect ultra-fine particles (UFPs) of less than 100 nm in diameter. Real-time measurements with engineered carbon NPs as well as carbon black NPs exhibited a zero-offset linear correlation to reference measurements using a standard fast mobility particle sizer (FMPS). A limit of detection (LOD) of better than 10 μg/m3 was found within a response time of 6 min, i.e., a typical short-term NP exposure duration. © 2015 IEEE.

Hamdana G.,TU Braunschweig | Hamdana G.,Laboratory for Emerging Nanometrology LENA | Wasisto H.S.,TU Braunschweig | Wasisto H.S.,Laboratory for Emerging Nanometrology LENA | And 6 more authors.
Optical Engineering | Year: 2016

A transferable force calibration standard based on a silicon microelectromechanical sensor has been designed, fabricated, and characterized for micrometrology applications. Two essential elements of double-meander springs and full piezoresistive etched p-silicon-on-insulator Wheatstone bridges (WBs) are integrated to the sensor for enhancing the device's sensitivity and eliminating the current leakage during an active sensing operation, respectively. The design process is supported by three-dimensional finite element modeling to select the optimal proposed sensors as well as simulating their mechanical and electrical properties in the desired force range (≤1000 μN). To fabricate the microforce sensors, a bulk micromachining technology is used by frequently involving an inductively coupled plasma deep reactive ion etching at cryogenic temperature. Several optical and electrical characterization techniques have been utilized to ensure the quality of the fabricated WBs, where their measured offset voltage can be down to 0.03±0.071 mV/V. In terms of its linearity, the fabricated device exhibits a small nonlinearity of <3%, which leads this sensor to be appropriate for precise microforce standard. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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