Baykal Sarioglu

Design and fabrication of two-axis micromachined steel scanners

This paper presents the fabrication and the test results of two-axis micromachined micro-mirror steel scanners developed for display and imaging applications. The novel fabrication method uses the conventional lithography and electrochemical metal etching techniques. A single photomask is used to define the whole structure, resulting in a simple and inexpensive fabrication process. Two different devices are designed, fabricated and characterized to test the proposed methods. Both of them employ the magnetostatic actuation to generate excitation force/torque. First device (Type-A) is a gimballed cantilever one, and it is capable of an optical scanning angle of 11.7° and 23.2° in slow- and fast-scan directions, consuming a power of 42 mW and 30.6 mW, respectively. This structure has a quality factor of 287 in the slow-scan direction and a quality factor of 195 in the fast-scan one. The second device (Type-B) is a gimballed torsional one, and it has an optical scanning angle of 76° and 5.9° in slow- and fast-scan directions, consuming 37 mW and 39 mW, respectively. This structure has a quality factor of 132 in the slow-scan and 530 in the fast-scan directions, respectively. The maximum total optical scanning angles obtained for the slow- and fast-scan axes are 105° (gimballed torsional device, Type-B) and 42° (gimballed cantilever device, Type-A).

Optoelectronic CMOS Power Supply Unit for Electrically Isolated Microscale Applications

This paper presents a CMOS power supply unit for electrically isolated microscale applications, where the provision of electrical power is not appropriate through wiring. A miniature fiberoptic platform consisting of an inclined silicon mirror fabricated using bulk micromachining is coupled to the monolithically integrated photodiode/dc-dc converter system, to yield a stand-alone optical power supply. In this approach, the dc/dc converter steps up the voltage of a single CMOS-integrated photodiode to a higher level. A test chip is fabricated using UMC 0.18-μm triple-well CMOS technology to demonstrate the power supply unit. Two different types of photodiodes, namely, a triple-well photodiode and an n-well photodiode are compared. It is found that on-chip triple-well photodiode results in a projected responsivity of 26 mA/W. The dc/dc converter had a maximum efficiency of 56% and is able to boost an input voltage level of 0.5-to-1.2 V. Silicon mirrors coated with 25-nm-thick aluminum are measured to have a reflectivity of 80% for a laser beam at a wavelength of 650 nm. Capability of the overall packaged optoelectronic system, consisting of the optical fiber, silicon mirror, CMOS photodiode, and the dc/dc converter, is demonstrated by generation of an electrical power of 60 μW.

An Optically Powered CMOS Receiver System for Intravascular Magnetic Resonance Applications

This paper presents a low-power optically powered receiver system designed in 0.18 μm triple well UMC complementary metal-oxide-semiconductor (CMOS) technology. Optical transmission is used for both power delivery and signal transmission. The power of the whole system can be supplied in two different configurations, namely continuous and intermittent mode configurations. In the continuous mode configuration, the optical power of a 650-nm laser source is received and delivered to the electronic circuits by a set of on-chip CMOS photodiodes. In the intermittent mode configuration, a low voltage DC-DC converter is used to boost a single on-chip CMOS photodiode voltage of 0.65 V up to 1.8 V. Additionally, in this configuration, optical switching is used for charging and discharging of a storage capacitor to obtain currents in milliampere range for the proper operation. The front-end part of the receiver consists of a fully differential low noise amplifier (LNA), a fully differential gain stage, a single output double balanced Gilbert-cell mixer, and a laser driver. The front-end part can operate properly by one on-chip photodiode voltage of 0.65 V . System performance is demonstrated for a sample 1.5 T magnetic resonance imaging (MRI) application. Experiments show that LNA of the receiver has a low input referred noise voltage density of 4 nV/√{Hz} at the supply voltage of 0.65 V . The receiver transmits the signal via a fiber-coupled infrared (IR) laser diode (λ = 1310 nm). The results show that the system can continuously process a minimum detectable signal (MDS) of -70 dBm at an incident optical power of 20 mW while the total power consumption of the receiver and the IR diode is 700 μW . In the intermittent mode configuration, the system gain is measured to be 6 dB greater, and the average power consumption is measured as 214 μW when the incident laser is modulated with a rectangular pulse wave of 40 ms period with 95% duty cycle.

An Optically Powered CMOS Tracking System for 3 T Magnetic Resonance Environment

In this work, a fully optical Complementary Metal Oxide Semiconductor (CMOS) based catheter tracking system designed for 3 T Magnetic Resonance Imaging (MRI) environment is presented. The system aims to solve the Radio Frequency (RF) induced heating problem present in conventional wired catheter tracking systems used in MRI. It is based on an integrated circuit, consisting of a receiver and an optical power supply unit. The optical power supply unit includes a single on-chip photodiode and a DC-DC converter that boosts the low photodiode voltage output to voltages greater than 1.5 V. Through an optically driven switch, the accumulated charge on an a storage capacitor is transferred to the rest of the system. This operation is novel in the way that it is fully optical and the switch control is done through modulation of the applied light. An on-chip local oscillator signal for the receiver is avoided by application of an RF signal that is generated by the MRI machine at the receiving period. The signals received by a micro-coil antenna are processed by the on-chip direct conversion receiver. The processed signal is then transferred, also optically, to the outside world for tracking purposes. The frequency encoding method is used for MRI tracking. Operation with various levels of external optical power does not generate noticeble temperature increase in the system. The overall system is successfully tested in a 3 T MRI machine to demonstrate its full operation.

Photodiodes for Monolithic CMOS Circuit Applications

An optoelectrical power supply unit compatible with standard CMOS processes designed for microscale applications is presented. The system is based on an earlier version consisting of a photodiode that converts optical power to electrical power, and a dc/dc converter that increases the photodiode anode voltage to desirable levels. It has the ability to operate continuously or intermittently. The latter operation mode employs additional system elements and requires the modulation of the input laser beam. A prototype was fabricated in UMC 0.18-μm triple-well standard CMOS process along with a direct conversion self-mixing receiver block on a die of 1525 μm × 1525 μm area. Performance measurements were done using a laser source of 650-nm wavelength at different power levels. For an input laser power of 80 mW, the source can provide an output current of 2.18 mA at a supply voltage of 1.2 V. The proposed system can be used to power integrated digital and low-power analog communication and medical microsystems.

LED integrated miniaturized polymer MEMS display

This study presents the process development and first experimental results of LED integrated polymer microelectromechanical systems (MEMS) for two-dimensional displays. Proposed integrated system is very cheap due to the fabrication simplicity and the choice of polymer material as the structural layer, and it is a strong candidate to show similar performance when compared with the existing flat panel displays. A process technology that enables the integration of the LED dies and the PCB-based MEMS structure is presented. The very first version of the MEMS structure is actuated by consuming 11.5 mW and resulting displacement is measured to be 9 mm. Along with the LED die size of 250 mum times 250 mum, 36 pixels of resolution can be achieved.

Statistical analysis of threshold algorithms in image processing based cancer cell detection

In this paper, an algorithm which is implemented for cancer detection in image processing and the results of the algorithm are mentioned. Researched work has three main steps. In first step, images are passed through significant steps for noise removal; at the second step, various histogram thresholds are calculated and at the last step cancer is detected with respect to calculated thresholds. As a result, the highest success rate is obtained as 81.25 percent while the lowest success rate is 37.5 percent.

Ultra low power all-digital CMOS sensor read out circuit for optically powered biomedical systems

In this paper, an ultra low power all digital sensor read out circuit architecture which requires very low power is proposed. The proposed circuit is targeted for optically powered biomedical applications. The read-out circuit is utilized for the measurement of capacitive and resistive type of transducers. The measurement method is based on the fact that both capacitive and resistive sensors can be utilized to introduce delay in the signal transmission path. The proposed circuit architecture is composed of entirely digital components and it measures the introduced delay using only single input clock signal. The proposed architecture is implemented on UMC 180 nm CMOS technology and simulation results are presented. The proposed circuit operates with 1.2 V supply that is generated by the optical power harvesting and charge pump unit, while consuming 70.4 mW. The results confirm that the proposed circuit can be utilized in optically powered biomedical applications for carrying out capacitive and resistive sensor measurements.

CMOS optical receiver for low power biomedical microsystems

In this paper, an integrated CMOS optical receiver in which optical power delivery and optical communication realized on a single channel is proposed. Pulse Width Modulation (PWM) method is applied on the light source for transmission of the signals. Clock, data and power signals are obtained by various filtering methods. The proposed receiver is designed in 180 nm UMC Standard CMOS technology and can operate with single integrated CMOS photodiode.

3D printed capacitive pressure sensor with corrugated surface

In this work a novel 3D printed capacitive pressure sensor with a corrugated surface is presented. The design composed of top and bottom plates. The sensor is 3D printed using a commercially available polymer material and then coated with Cr and Au with sputtering process. The dimensions of produced structure that designed is 11 × 11 × 4.6mm3. Due to the corrugated surface, the area of the plates is increased 19.46% compared to a standard flat surface parallel plate capacitive sensor in the same bulk area. The design process of the sensor, simulation and the experimental results are given and explained in detail. The performance of the sensor is tested with various pressure levels between 0 Pa and 8.88 kPa. The experimental results show that the capacitance range of the sensor is 2.7 pF-4.3 pF. The maximum sensitivity of the sensor is obtained as 0.14 pF / kPa. The results confirm that the presented capacitive sensor can be utilized for carrying out pressure measurements.