Device modelling for bendable piezoelectric FET-based touch sensing system

Flexible electronics is rapidly evolving towards devices and circuits to enable numerous new applications. The high-performance, in terms of response speed, uniformity and reliability, remains a sticking point. The potential solutions for high-performance related challenges bring us back to the timetested silicon based electronics. However, the changes in the response of silicon based devices due to bending related stresses is a concern, especially because there are no suitable models to predict this behavior. This also makes the circuit design a difficult task. This paper reports advances in this direction, through our research on bendable Piezoelectric Oxide Semiconductor Field Effect Transistor (POSFET) based touch sensors. The analytical model of POSFET, complimented with Verilog-A model, is presented to describe the device behavior under normal force in planar and stressed conditions. Further, dynamic readout circuit compensation of POSFET devices have been analyzed and compared with similar arrangement to reduce the piezoresistive effect under tensile and compressive stresses. This approach introduces a first step towards the systematic modeling of stress induced changes in device response. This systematic study will help realize high-performance bendable microsystems with integrated sensors and readout circuitry on ultra-thin chips (UTCs) needed in various applications, in particular, the electronic skin (e-skin)

Label-free CMOS Bio Sensor with On-chip Noise Reduction Scheme for Real-time Quantitative Monitoring of Biomolecules

We present a label-free CMOS field-effect transistor sensing array to detect the surface potential change affected by the negative charge in DNA molecules for real-time monitoring and quantification. The proposed CMOS bio sensor includes a new sensing pixel architecture implemented with correlated double sampling for reducing offset fixed pattern noise and 1/f noise of the sensing devices. We incorporated non-surface binding detection which allows real-time continuous monitoring of DNA concentrations without immobilizing them on the sensing surface. Various concentrations of 19-bp oligonucleotides solution can be discriminated using the prototype device fabricated in 1-??m double-poly double-metal standard CMOS process. The detection limit was measured as 1.1 ng/??l with a dynamic range of 40 dB and the transient response time was measured less than 20 seconds. © 2011 IEEE.close5

Label-free detection of biomolecules with Ta2O5-based field effect devices

Dissertação para obtenção do Grau de Doutor em Nanotecnologias e NanociênciasInternational Iberian Nanotechnology Laboratory (INL

Quantitative Optical Sensing for Non-Invasive Clinical Characterization of Biological Tissues.

It is well known that changes in tissue morphology and/or biochemistry can affect tissue function. Characterizing these changes in tissue function through non-invasive and label-free assessment can inform clinical practice and improve patient outcomes. In this thesis, we employ non-invasive, quantitative, label-free, portable, and clinically-compatible reflectance and fluorescence spectroscopic technology for use in two clinical challenges: (1) improved detection of pancreatic disease and (2) post-implantation monitoring of tissue-engineered construct wound healing in an in situ murine model. (1) Only 6% of pancreatic cancer patients survive 5 years after diagnosis, making it the 4th leading cause of cancer death in the United States. To improve detection of pancreatic cancer, we studied the diagnostic utility of optical spectroscopy to detect pancreatic disease in 5 Stages, with Stages 1 and 2 previously reported. Stage 1 showed that ex vivo measurements of human adenocarcinoma tissue correspond well to in vivo measurements from a tumor xenograft in a murine model. Stage 2 showed that malignant tissues measured ex vivo distinguish malignant and benign tissues. In this thesis, we discuss Stages 3-5. In Stage 3, a photon-tissue interaction (PTI) model was verified with measurements from tissue-simulating phantoms and validated with measurements from a subset of ex vivo human tissues collected in Stage 2. We show that a calibrated PTI model consistently extracts biologically-relevant optical tissue scattering parameters in the presence of variable hemoglobin absorption. In Stage 4, we perform the first ever, to our knowledge, in vivo feasibility study employing optical steady-state spectroscopy to detect malignant tissues during open surgery. In Stage 5, we investigate time-resolved fluorescence spectroscopy ex and in vivo to improve pancreatic disease classification. Furthermore, we show the first ever human pancreatic tissue measurements with an endoscopically-compatible fiber-optic probe. (2) Regulatory approval for tissue-engineered combinational devices, including tissue constructs developed for human implantation, requires reliable methods to assess post-implantation wound healing in vivo, of which none currently exist. In this thesis, we investigate diffuse reflectance spectroscopy to detect hallmarks of graft wound healing, including tissue revascularization, cell proliferation, and cell density, based on construct absorption and scattering properties.PHDBiomedical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/107084/1/billlloy_1.pd