Adversarially Trained Autoencoders for Parallel-Data-Free Voice Conversion

We present a method for converting the voices between a set of speakers. Our method is based on training multiple autoencoder paths, where there is a single speaker-independent encoder and multiple speaker-dependent decoders. The autoencoders are trained with an addition of an adversarial loss which is provided by an auxiliary classifier in order to guide the output of the encoder to be speaker independent. The training of the model is unsupervised in the sense that it does not require collecting the same utterances from the speakers nor does it require time aligning over phonemes. Due to the use of a single encoder, our method can generalize to converting the voice of out-of-training speakers to speakers in the training dataset. We present subjective tests corroborating the performance of our method

Nanoscale thickness silicon -on -insulator field effect devices for bio-chemical sensing and heat mediated chemical reactions

Semiconductor field effect sensors have been shown to enable the possibility of realizing cost effective, highly dense label-free sensors for the detection of chemical and biological species. Such sensors can be readily integrated with existing platforms for micro total analysis systems, or lab-on-a chip systems. Field effect devices realized using nanowires, or other materials and structures have proven to provide detection sensitivity and selectivity far surpassing current clinical alternatives. In addition, if silicon field effect transistors could be used as nanoscale temperature controllers in a fluidic environment, this would add a new dimension to the versatility of these nanoscale devices. These multi-functional transistors will find broad applications in many systems that had thus far required separate components for each function. Such systems may range from the realization of densely integrated sensors with active surfaces to rapid and local polymerase chain reaction (PCR) systems with integrated sensing. In this dissertation, the fabrication and operation of silicon-on-insulator field effect devices utilizing conventional microfabrication techniques is demonstrated towards realizing such sensor/heater hybrids. The fabrication technique makes the devices amenable for large scale fabrication and seamless integration with existing platforms. Optimization of the device operation is performed by utilizing the inherent pH sensitivity of the devices. Bio-molecular sensing is demonstrated using DNA detection as a model system. The additional functionality of localized heating in fluid using the same devices is also shown, and characterized by temperature dependent fluorescence intensity modulation. Selective functionalization of DNA molecules as well as heat mediated localized exchange reactions on the devices are demonstrated as model applications

Localized heating and thermal characterization of high electrical resistivity silicon-on-insulator sensors using nematic liquid crystals

We present a method for localized heating of media at the surface of silicon-on-insulator field-effect sensors via application of an ac voltage across the channel and the substrate and compare this technique with standard Joule heating via the application of dc voltage across the source and drain. Using liquid crystals as the medium to enable direct temperature characterization, our results show that under comparable bias conditions, heating of the medium using an alternating field results in a greater increase in temperature with a higher spatial resolution. These features are very attractive as devices are scaled to the nanoscale dimensions. (C) 2008 American Institute of Physics

Nanoscale thickness double-gated field effect silicon sensors for sensitive pH detection in fluid

In this work, we report on the optimization of a double-gate silicon-on-insulator field effect device operation to maximize pH sensitivity. The operating point can be fine tuned by independently biasing the fluid and the back gate of the device. Choosing the bias points such that device is nearly depleted results in an exponential current response-in our case, 0.70 decade per unit change in pH. This value is comparable to results obtained with devices that have been further scaled in width, reported at the forefront of the field, and close to the ideal value of 1 decade/pH. By using a thin active area, sensitivity is increased due to increased coupling between the two conducting surfaces of the devices

Surface immobilizable chelator for label-free electrical detection of pyrophosphate

A new pyrophosphate (PPi) chelator was designed for surface-sensitive electrical detection of biomolecular reactions. This article describes the synthesis of the PPi-selective receptor, its surface immobilization and application to label-free electrical detection on a silicon-based field-effect transistor (FET) sensor

Silicon Field Effect Transistors as Dual-Use Sensor-Heater Hybrids

We demonstrate the temperature mediated applications of a previously proposed novel localized dielectric heating method on the surface of dual purpose silicon field effect transistor (FET) sensor-heaters and perform modeling and characterization of the underlying mechanisms. The FET\u27s are first shown to operate as electrical sensors via sensitivity to changes in pH in ionic fluids. The same devices are then demonstrated as highly localized heaters via investigation of experimental heating profiles and comparison to simulation results. These results offer further insight into the heating mechanism and help determine the spatial resolution of the technique. Two important biosensor platform applications spanning different temperature ranges are then demonstrated: a localized heat mediated DNA exchange reaction and a method for dense selective functionalization of probe molecules via the heat catalyzed complete desorption and reattachment of chemical functionalization to the transistor surfaces. Our results show that the use of silicon transistors can be extended beyond electrical switching and field-effect sensing to performing localized temperature controlled chemical reactions on the transistor itself