Application specific DAC and ADC for a bio-impedance measurement circuit

A transistor level implementation of a 3 bit digital harmonic canceling (DHC) digital to analog converter (DAC), and a 10 bit successive approximation register (SAR) analog to digital converter (ADC) is designed. The circuits are intended to be a part of a bio-impedance measurement system in which a current is injected into the myocardium tissue and blood pool for the purpose of determining the heart’s stroke volume. The DHC DAC injects a 100 μA[subscript rms] current at a 20 kHz fundamental frequency using appropriately weighted current mirrors from a 160 kHz square-wave reference clock. A [function subscript s] = 160 kS/s ADC is designed with synchronous SAR logic, bottom-plate sampling, and a charge-redistribution capacitive DAC.Electrical and Computer Engineerin

An Immunofluorescence-assisted Microfluidic Single Cell Quantitative Reverse Transcription Polymerase Chain Reaction Analysis of Tumour Cells Separated from Blood

Circulating tumour cells (CTCs) are important indicators of metastatic cancer and may provide critical information for individualized treatment. As CTCs are usually very rare, the techniques to obtain information from very small numbers of cells are crucial. Here, we propose a method to perform a single cell quantitative reverse transcription polymerase chain reaction (qPCR) analysis of rare tumour cells. We utilized a microfluidic immunomagnetic assay to separate cancer cells from blood. A combination of detailed immunofluorescence and laser microdissection enabled the precise selection of individual cells. Cancer cells that were spiked into blood were successfully separated and picked up for a single cell PCR analysis. The breast cancer cell lines MCF7, SKBR3 and MDAMB231 were tested with 10 different genes. The result of the single cell analysis matched the results from a few thousand cells. Some markers (e.g., ER, HER2) that are commonly used for cancer identification showed relatively large deviations in expres‐ sion levels. However, others (e.g., GRB7) showed devia‐ tions that are small enough to supplement single cell disease profiling