Sebastian Gautsch

Two dimensional array of piezoresistive nanomechanical Membrane-type Surface Stress Sensor (MSS) with improved sensitivity.

We present a new generation of piezoresistive nanomechanical Membrane-type Surface stress Sensor(MSS) chips, which consist of a two dimensional array of MSS on a single chip. The implementation of several optimization techniques in the design and microfabrication improved the piezoresistive sensitivity by 3∼4 times compared to the first generation MSS chip, resulting in a sensitivity about ∼100 times better than a standard cantilever-type sensor and a few times better than optical read-out methods in terms of experimental signal-to-noise ratio. Since the integrated piezoresistive read-out of the MSS can meet practical requirements, such as compactness and not requiring bulky and expensive peripheral devices, the MSS is a promising transducer for nanomechanical sensing in the rapidly growing application fields in medicine, biology, security, and the environment. Specifically, its system compactness due to the integrated piezoresistive sensing makes the MSS concept attractive for the instruments used in mobile applications. In addition, the MSS can operate in opaque liquids, such as blood, where optical read-out techniques cannot be applied.

MEMS for space

Future space exploration will emphasize on cost effectiveness and highly focused mission objectives. Missions costs are directly proportional to its total weight, thus, the trend will be to replace bulky and heavy components of space carriers, communication and navigation platforms and of scientific payloads.

Double-Side-Coated Nanomechanical Membrane-Type Surface Stress Sensor (MSS) for One-Chip-One-Channel Setup

With their capability for real-time and label-free detection of targets ranging from gases to biological molecules, nanomechanical sensors are expected to contribute to various fields, such as medicine, security, and environmental science. For practical applications, one of the major issues of nanomechanical sensors is the difficulty of coating receptor layers on their surfaces to which target molecules adsorb or react. To have measurable deflection, a single-side coating is commonly applied to cantilever-type geometry, and it requires specific methods or protocols, such as inkjet spotting or gold-thiol chemistry. If we can apply a double-side coating to nanomechanical sensors, it allows almost any kind of coating technique including dip coating methods, making nanomechanical sensors more useful with better user experiences. Here we address the feasibility of the double-side coating on nanomechanical sensors demonstrated by a membrane-type surface stress sensor (MSS) and verify its working principle by both finite element analysis (FEA) and experiments. In addition, simple hand-operated dip coating is demonstrated as a proof of concept, achieving practical receptor layers without any complex instrumentation. Because the double-side coating is compatible with batch protocols such as dip coating, double-side-coated MSS represents a new paradigm of one-chip-one-channel (channels on a chip are all coated with the same receptor layers) shifting from the conventional one-chip-multiple-channel (channels on a chip are coated with different receptor layers) paradigm.

In-plane fabricated insulated gold-tip probe for electrochemical and molecular experiments

In this contribution we present a scanning probe with a gold-tip completely encapsulated with insulator all the way to the apex. The probe fabrication is unique owing to an in-plane arrangement in which the width of the cantilever is defined by deep reactive ion etching (DRIE). E-beam lithography was employed for defining the gold nanowire tip. The cantilever and the chip body were defined by DRIE in later steps. The radius of curvature of the tip apex is around 20 nm. The high-quality insulation on the tip was demonstrated by performing electrodeposition of gold. The spring constant of the cantilever was obtained by measuring the resonance frequency of the cantilever. With this in-plane fabrication process, probes with different spring constants ranging from 0.1 N/m to 9 N/m were fabricated on the same wafer.

NEMS based tools for nanoscience and atomic clocks

Nanoscience is a thriving multi-disciplinary activity, which aims at understanding the properties and the interaction of very small objects on the nanometer scale. In this endeavor, tools for the observation, analysis and modification of individual objects like macromolecules, clusters or even single atoms are required. The development of dedicated microfabricated instruments to measure physical and chemical interactions at this scale is therefore required. This talk will give an overview of microfabrication techniques employed to shape such NEMS based tools and introduce the audience to several probing techniques. In a second part, we focus on the principles and fabrication techniques of atomic clocks.