Walter Haeberle

Microfabrication and parallel operation of 5/spl times/5 2D AFM cantilever arrays for data storage and imaging

In this paper we report on the microfabrication of a 5/spl times/5 2D cantilever array and its successful application to parallel imaging. The 5/spl times/5 array with integrated force sensing and tip heating has been fabricated using a recently developed, all dry silicon backside etching process. The levers on the array have integrated piezoresistive sensing. The array is scanned in x and y directions using voice coil actuators. Three additional voice coil z actuators are used in a triangular arrangement to approach the sample with the array chip. The system is thus leveled in the same way as an air table. We report details of the array fabrication, the x-y scanning and approach system as well as images taken with the system.

Dual-Stage Nanopositioning for High-Speed Scanning Probe Microscopy

This paper presents a dual-stage approach to nanopositioning in which the tradeoff between the scanner speed and range is addressed by combining a slow, large-range scanner with a short-range scanner optimized for high-speed, high-resolution positioning. We present the design, finite-element simulations, and experimental characterization of a fast custom-built short-range scanner. The short-range scanner is based on electromagnetic actuation to provide high linearity, has a clean, high-bandwidth dynamical response and is equipped with a low-noise magnetoresistance-based sensor. By using advanced noise-resilient feedback controllers, the dual-stage system allows large-range positioning with subnanometer closed-loop resolution over a wide bandwidth. Experimental results are presented in which the dual-stage scanner system is used for imaging in a custom-built atomic force microscope.

Massively Parallelized Pollen Tube Guidance and Mechanical Measurements on a Lab-on-a-Chip Platform

Pollen tubes are used as a model in the study of plant morphogenesis, cellular differentiation, cell wall biochemistry, biomechanics, and intra- and intercellular signaling. For a “systems-understanding” of the bio-chemo-mechanics of tip-polarized growth in pollen tubes, the need for a versatile, experimental assay platform for quantitative data collection and analysis is critical. We introduce a Lab-on-a-Chip (LoC) concept for high-throughput pollen germination and pollen tube guidance for parallelized optical and mechanical measurements. The LoC localizes a large number of growing pollen tubes on a single plane of focus with unidirectional tip-growth, enabling high-resolution quantitative microscopy. This species-independent LoC platform can be integrated with micro-/nano-indentation systems, such as the cellular force microscope (CFM) or the atomic force microscope (AFM), allowing for rapid measurements of cell wall stiffness of growing tubes. As a demonstrative example, we show the growth and directional guidance of hundreds of lily (Lilium longiflorum) and Arabidopsis (Arabidopsis thaliana) pollen tubes on a single LoC microscopy slide. Combining the LoC with the CFM, we characterized the cell wall stiffness of lily pollen tubes. Using the stiffness statistics and finite-element-method (FEM)-based approaches, we computed an effective range of the linear elastic moduli of the cell wall spanning the variability space of physiological parameters including internal turgor, cell wall thickness, and tube diameter. We propose the LoC device as a versatile and high-throughput phenomics platform for plant reproductive and development biology using the pollen tube as a model.

A dual-stage nanopositioning approach to high-speed scanning probe microscopy

A novel positioning concept for high-speed scanning probe microscopy is presented in which a dual-stage nanopositioner is used for precise positioning over large areas at high speeds. The nanopositioner combines a low-bandwidth, large-range commercial scanner with a custom-designed high-speed scanner for short-range positioning. We present the mechanical design, finite element simulations and experimental characterization of the high-speed scanner, showing exceptionally clean dynamics, high linearity and large actuation bandwidth. The scanner is equipped with a magneto-resistive position sensing scheme that provides subnanometer resolution over a large bandwidth. Advanced model-based feedback controllers are designed according to a newly developed control design architecture with direct shaping of the closed-loop noise sensitivity and experimental results are presented in which the dual-stage system is used for high-speed imaging in a custom-built atomic force microscope.

A high-speed electromagnetically-actuated scanner for dual-stage nanopositioning

Abstract This paper presents the mechanical design, finite element simulations and experimental verification of an electromagnetically-actuated uniaxial high-speed nanopositioner. The nanopositioner is designed specifically as a fast, short-range scanner for a dual-stage nanopositioning system. To that end, the scanner has high linearity owing to its electromagnetic actuation and well-defined dynamic behavior over a large bandwidth. There was significant emphasis on reducing the mechanical and thermal coupling from the actuation block. Using model-based feedback controllers with direct shaping of the closed-loop noise transfer function, experimental results are presented in which the scanner is integrated in a dual-stage nanopositioning system and used for high-speed imaging in a custom-built atomic force microscope.

201 Gb/in 2 Recording Areal Density on Sputtered Magnetic Tape

A prototype perpendicularly oriented sputtered tape sample was investigated using a prototype high-moment tape write head and a 48 nm-wide tunneling magnetoresistive hard disk drive read head. A linear density of 818 kbpi with a post-detection byte-error rate <0.023 was demonstrated based on measured recording data and a software read channel that used an extended version of the noise-predictive maximum-likelihood detection scheme that tracks the mean of the data-dependent noise. Using a previously reported iterative decoding architecture, a user bit-error rate of <1e–20 can be achieved at this operating point. Track-following servo performance characterized by the standard deviation of the position error signal (

Technologies for magnetic tape recording at 100Gb/in 2 and beyond

\sigma

29.5-

-PES) ≤ 6.5 nm was also demonstrated over a tape speed range of 1.2–4.1 m/s. This magnitude of PES in combination with a 48 nm-wide reader enables reliable recording at a track width of 103 nm corresponding to a track density of 246.2 ktpi, for an equivalent areal density of 201.4 Gb/in2.

\hbox{Gb/in}^{2}

Magnetic tape systems provide high reliability storage at a low total cost of ownership and are well suited for the long term storage of less frequently accessed data. The current explosive growth rate of digital data is driving demand for cost effective storage technologies and has resulted in a renaissance in applications for tape systems. Current state of the art tape systems operate with areal densities up to ~6 Gb/in2 and provide cartridge capacities up to 10TB. The future success of tape systems depends on continued areal density and capacity scaling to maintain or increase the current cost advantage of tape over competing technologies. In this work we describe a set of technologies that enable the scaling of tape recording to areal densities of 100 Gb/in2 and beyond.