Lian Leng

CMOS Neurotransmitter Microarray: 96-Channel Integrated Potentiostat With On-Die Microsensors

A 8 × 12 array of integrated potentiostats for on-CMOS neurotransmitter imaging is presented. Each potentiostat channel measures bidirectional redox currents proportional to the concentration of a neurochemical. By combining the current-to-frequency and the single-slope analog-to-digital converter (ADC) architectures a total linear dynamic range of 95 dB is achieved. A 3.8 mm × 3.1 mm prototype fabricated in a 0.35 μm standard CMOS technology was integrated with flat and 3D on-die gold microelectrodes and an on-chip microfluidic network. It is experimentally validated in in-situ recording of neurotransmitter dopamine.

A CMOS-Microfluidic Chemiluminescence Contact Imaging Microsystem

A hybrid CMOS-microfluidic microsystem for chemiluminescence and electrochemiluminescence-based biochemical sensing is presented. The microsystem integrates a two-layer soft polymer microfluidic network and a CMOS imager fabricated in a standard 0.35-μm technology. The CMOS imager consists of a 64 × 128-pixel array interdigitated with a 32 × 64 electrolessly plated nickel-gold microelectrode array. A two-transistor reset path technique attenuates the subthreshold leakage current of the reset transistor which constitutes a significant portion of the dark current. An active reset technique, in-pixel flicker noise cancellation, and pixel binning contribute to noise reduction. The imager achieves a low dark current of 3.6 nA/cm2 for photodiode reset voltages as high as 2.3 V, noise of 110 μVrms with maximum time of photon integration of 90 s, and a dynamic range of 67.8 dB. The CMOS-microfluidic microsystem is validated in on-chip chemiluminescence and electrochemiluminescence detection of luminol.

192-channel CMOS neurochemical microarray

A 16×12-channel neurochemical microarray is presented. Each channel acquires bidirectional currents down to pico-amperes proportional to the concentration of a neurochemical. By combining the current-to-frequency and the single-slope analog-to-digital converter (ADC) 110dB of dynamic range is achieved. The ADC in each channel generates a 16-bit output in less than a millisecond. The microarray with flat and 3D gold electrodes and an on-chip microfluidic network is experimentally validated in in-situ recording of neurotransmitter dopamine.

A hybrid CMOS-microfluidic contact imaging microsystem

A hybrid CMOS/Microfluidic microsystem is presented. The microsystem integrates a soft polymer microfluidic network with a 64x128 pixel imager fabricated in low-cost standard 0.35 micron CMOS technology. The multiple microfluidic channels facilitate in-situ photochemical reactions of analytes and their detection directly on the surface of the CMOS photosensor array. The promixity between the analyte and the photosensor enhances the microsystem sensitivity, thus requiring only microliter volumes of the sample. Circuit techniques such as pixel binning and a two transistor reset path technique are employed to improve the imager sensitivity. The integrated microsystem is validated in on-chip chemiluminescence detection of luminol for the two microfluidic network prototypes designed.