The Photosynthesiser - A methodology for mapping environmental conditions, pivotal to the speed of photosynthesis in plants, through sonification.

Traditionally, the close inspection of data requires visual guidance in the form of displays depicting numeric or graphical representations over time. Sonification offers a way to convey this data through auditory means, relinquishing the need for constant display monitoring. To enable horticulturists to continue to move and work around their environment a proposed sonification mapping system for the key environmental conditions, vital for optimum levels of photosynthesis, has been developed. The outcome of this research was to provide a monitoring system that was both musical and meaningful with regards to data fluctuations and most importantly, could be interpreted by a wide demographic of listeners. A literature review provides an underpinning to both the scientific and artistic merits of sonification whilst a practice-based model was used to develop appropriate musical timbres, offering a natural instrumentation through physical modelling synthesis. Key questions around which musical factors can be used to trigger specific emotions and which of these emotions do we associate with an environment that offers a higher rate or low rate of photosynthesis for plants are explored. Through literary research as well as the deployment and analysis of surveys, a list of musical parameters was identified and a mapping framework designed. To analyse the success of the design, an audio installation was constructed within grounds at the Eden Project. The environmental data of both biomes, tropical and Mediterranean, were sonified into two musical streams and visitors surveyed through quantitative and qualitative methods in an experiment to see if they could correctly associate the music to the biome. The results provided 90% accuracy in the correct identification. It is theorised through this research that the mapping framework designed can be used in the sonification of climate conditions and communicate key traits within each environment

Research on Microelectronics and Nanotechnologies at Georgia Tech

The presentation provides an overview of the nanotechnology fabrication resources available at Georgia Tech’s Institute for Electronics and Nanotechnology (IEN) and highlights some of the research activities enabled by them. The IEN cleanrooms and characterization labs are part of the NSF-funded National Nanotechnology Coordinated Infrastructure (NNCI) and are used by almost 700 researchers on an annual base. Supported activities range from materials and process development to micro/nano device and system integration

Interaural time difference processing in the mammalian medial superior olive

The dominant cue for localization of low-frequency sounds are microsecond differences in the time-of-arrival of sounds at the two ears [interaural time difference (ITD)]. In mammals, ITD sensitivity is established in the medial superior olive (MSO) by coincidence detection of excitatory inputs from both ears. Hence the relative delay of the binaural inputs is crucial for adjusting ITD sensitivity in MSO cells. How these delays are constructed is, however, still unknown. Specifically, the question of whether inhibitory inputs are involved in timing the net excitation in MSO cells, and if so how, is controversial. These inhibitory inputs derive from the nuclei of the trapezoid body, which have physiological and structural specializations for high-fidelity temporal transmission, raising the possibility that well timed inhibition is involved in tuning ITD sensitivity. Here, we present physiological and pharmacological data from in vivo extracellular MSO recordings in anesthetized gerbils. Reversible blockade of synaptic inhibition by iontophoretic application of the glycine antagonist strychnine increased firing rates and significantly shifted ITD sensitivity of MSO neurons. This indicates that glycinergic inhibition plays a major role in tuning the delays of binaural excitation. We also tonically applied glycine, which lowered firing rates but also shifted ITD sensitivity in a way analogous to strychnine. Hence tonic glycine application experimentally decoupled the effect of inhibition from the timing of its inputs. We conclude that, for proper ITD processing, not only is inhibition necessary, but it must also be precisely timed

Cantilever-based Resonant Microsensors with Integrated Temperature Modulation for Transient Chemical Analysis

This work introduces a resonant cantilever platform with integrated temperature modulation for real-time chemical sensing. Embedded heaters allow for rapid thermal cycling of individual sensors, thereby enabling real-time transient signal analysis without the need for a microfluidic setup to switch between analyte and reference gases. Compared to traditional mass-sensitive microsensors operating in steady state, the on-chip generation of signal transients provides additional information for analyte discrimination

Transient Analysis of Analyte Desorption Due to Thermal Cycling with Varying Pulse Duration

This paper introduces heating pulse duration modulation on a chemically sensitive, polymer-coated resonant cantilever platform for analyte discrimination during the desorption phase. As in our previous work, the embedded heaters enable real-time measurements of analyte sorption into the polymer film, without the need for traditional valve systems and reference gases [1-2]. This work particularly looks at the effects of varying pulse lengths on the sensor responses, while holding the heating power constant. A model differential equation is developed for the sensor response based on both the device sensitivity and transient response. This model can then be used together with estimation theory for analyte identification and quantification, even in mixtures

A Multi-Modal Continuous-Systems Model of a Novel High-Q Disk Resonator in a Viscous Liquid

International audienc

Resonant Characteristics of Rectangular Microcantilevers Vibrating Torsionally in Viscous Liquid Media

The resonant characteristics of rectangular microcantilevers vibrating in the torsional mode in viscous liquid media are investigated. The hydrodynamic load (torque per unit length) on the vibrating beam due to the liquid was first determined using a finite element model. An analytical expression of the hydrodynamic function in terms of the Reynolds number and aspect ratio, h/b (with thickness, h, and width, b) was then obtained by fitting the numerical results. This allowed for the resonance frequency and quality factor to be investigated as functions of both beam geometry and medium properties. Moreover, the effects of the aspect ratio on the cross-section\u27s torsional constant, K, which affects the microcantilever\u27s torsional stiffness, and on its polar moment of inertia, Jp, which is associated with the beam\u27s rotational inertia, are also considered when obtaining the resonance frequency and quality factor. Compared with microcantilevers under out-of-plane (transverse) flexural vibration, the results show that microcantilevers that vibrate in their 1st torsional or 1st in-plane (lateral) flexural resonant modes have higher resonance frequency and quality factor. The increase in resonance frequency and quality factor results in higher mass sensitivity and reduced frequency noise, respectively. The improvement in the sensitivity and quality factor are expected to yield much lower limits of detection in liquid-phase chemical sensing applications

Resonant Characteristics of Rectangular Hammerhead Microcantilevers Vibrating Laterally in Viscous Liquid Media

The resonant characteristics of laterally vibrating rectangular hammerhead microcantilevers in viscous liquid media are investigated. The rectangular hammerhead microcantilever is modeled as an Euler-Bernoulli beam (stem) and a rigid body (head). A modified semi-analytical expression for the hydrodynamic function in terms of the Reynolds number, Re, and aspect ratio, h/b, is proposed to rapidly evaluate the sensing characteristics. Using this expression, the resonance frequency, quality factor and normalized surface mass sensitivity are investigated as a function of the dimensions of the microcantilever and liquid properties. Guidelines for design of hammerhead microcantilever geometry are proposed to achieve efficient sensing platforms for liquid-phase operation. The improvement in the sensing area and characteristics are expected to yield higher sensitivity of detection and improved signal-to-noise ratio in liquid-phase chemical sensing applications

An Analytical Model of a Thermally Excited Microcantilever Vibrating Laterally in a Viscous Fluid

To achieve higher quality factors (Q) for microcantilevers used in liquid-phase sensing applications, recent studies have explored the use of the lateral (in-plane) flexural mode. In particular, we have recently shown that this mode may be excited electrothermally using integrated heating resistors near the micro cantilever support, and that the resulting increase in Q helps to make low-ppb limits of detection a possibility in liquids. However, because the use of electrothermally excited, liquid-phase, microcantilever-based sensors in lateral flexure is relatively new, theoretical models are lacking. Therefore, we present here a new analytical model for predicting the vibratory response of these devices. The model is also used to successfully confirm the validity of our previously derived Q formula, which was based on a single-degree-of-freedom (SDOF) model and a harmonic tip force. Comparisons with experimental data show that the present model and, thus, the analytical formula provide excellent Q estimates for sufficiently thin beams vibrating laterally in water and reasonable upper-bound estimates for thicker beams