Multipurpose Drivers for MEMS Devices Based on a Single ASIC Implemented in a Low-Cost HV CMOS Process without a Triple Well

This paper presents a novel topology for multipurpose drivers for MEMS sensors and actuators, suitable for integration in low-cost high-voltage (HV) CMOS processes, without a triple well. The driver output voltage, V MEMS , can be programmed over a wide, symmetrical range of positive and negative values, with the maximum output voltage being limited only by the maximum drain-source voltage that the HV transistors can handle. The driver is also able to short its output to the ground line and to leave it floating. It comprises generators for large positive and negative voltages followed by an LDO for each polarity that ensures that V MEMS has a well-controlled level and a very low ripple. The LDOs also help implement the grounded- and floating-output operating modes. Most of the required circuitry is integrated within a HV CMOS ASIC: the drivers for the large voltage generators, the error amplifiers of the LDOs, the DAC used to program the V MEMS level, and their support circuits. Thus, only the power stages of the large voltage generators, the pass transistors of the LDOs and two resistors for the LDO feedback network are discrete. A suitable configuration was devised for the latter that allows for the external resistor network to be shared by the two LDOs and prevents negative voltages from developing at the ASIC pins. Two circuit implementations of the proposed topology, designed in a low-cost 0.18 μm HV CMOS process, are presented in some detail. Simulation results demonstrate that they realize the required operating modes and provide V MEMS voltages programmable with steps of 100 mV or 200 mV, between -20 V and +20 V or between −45 V and +45 V, respectively. The output voltage ripple is relatively small, just 3.4 mVpkpk for the first implementation and 17 mVpkpk for the second. Therefore, both circuits are suitable for biasing and controlling a wide range of MEMS devices, including MEMS mirrors used in applications such as endoscopic optical coherence tomography.

Using Endoscopic Optical Coherence Tomography to Detect and Treat Early-Stage Pancreatic Cancers

We developed a novel technology capable of detecting early-stage pancreatic cancers using high-resolution three-dimensional endoscopic optical coherence tomography (Endo-OCT), and treating them using high dose rate brachytherapy (HDR) under the Endo-OCT image guidance. This technology integrates our custom-built ultra-high resolution endoscopic three-dimensional OCT diagnostic imaging device with a commercial high dose rate brachytherapy system (HDR), resulting in a compact, portable, easy-to-operate, and low-cost Endo-OCT image-guided high dose rate brachytherapy (OCT-IGHDR) system. The system has the dual functions of diagnosis and treatment that can precisely detect and measure the location and size of the early-stage pancreatic cancer or premalignant lesions and then treat them from the inside of the pancreatic duct with an accurate and focused dose while greatly reducing the radiation toxicity to the neighboring tissues and organs. This minimally-invasive treatment technology could avoid the potential complications from surgery and reduces the high operation cost. This technology could also be applied to treat diseases of the esophagus, rectum, bronchus, and other aerodigestive organs that are suitable for use with an endoscopic device. In this article, we describe the concept of this technology and the preliminary experiments that could demonstrate the concept by using this homemade Endo-OCT machine to image the pancreatic duct for diagnosis of early-stage pancreatic cancer or premalignant lesions and to perform Endo-OCT image-guided brachytherapy.