We present a novel, multiparametric microphysiometry system for the dynamic online monitoring of human cancer cell metabolism. The optically transparent, modular, hybrid microsystem is based on a glass chip and combines a cell cultivation chamber, microfluidics and metabolic monitoring with fully integrated chemo- and biosensors. pH and oxygen are measured in the cell culture area, and biosensors for lactate and glucose are connected downstream by microfluidics. The wafer-level fabrication features thin-film platinum and iridium oxide microelectrodes on a glass chip, microfluidics in an epoxy resist, a hybrid assembly and an on-chip reference electrode. The reliable analytical performance of the sensors in cell culture medium was demonstrated. The pH sensors exhibit a long-term stable, linear response. The oxygen sensors show a linear behaviour, which is also observed for low oxygen concentrations. Glucose and lactate measurements show a linear, long-term stable, selective and reversible behaviour in the desired range. T98G human brain cancer cells were cultivated and cell culture metabolism was measured on-chip. Stop/flow cycles were applied and extracellular acidification, respiration, glucose consumption and lactate production were quantified. Long-term metabolic rates were determined and all parameters could be measured in the outlet channel. A placement downstream of the cell cultivation area for biosensors was realised. A highly effective medium exchange and undiluted sampling from the cell culture chamber with low flow rates (2 μl min⁻¹) and low volumes (15 μl per cycle) were achieved. The drug screening application was demonstrated by detecting alteration and recovery effects of cellular metabolism induced by the addition of substances to the medium.

We discuss microsensors for cell culture monitoring from 2D culture to organ-on-chip systems, including sensor principles, fabrication and culture formats.

An organ-on-chip platform equipped with microsensors for long-term microfluidic cultivation and metabolic monitoring (O ₂ , Glu, Lac) of 3D tumour organoid cultures grown from patient-derived single cancer stem cells.

Abstract