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We present here an electrochemical sensor microsystem for the monitoring of pH. The all-polymeric device is comprised of a cyclic olefin copolymer substrate, a 200 nm-thin patterned layer of conductive polymer (PEDOT), and a 70 nm electropolymerized layer of a pH sensitive conductive polymer (polyaniline). The patterning of the fluidic (microfluidic channels) and conductive (wiring and electrodes) functional elements was achieved with a single soft PDMS mold via a single embossing step process. A post-processing treatment with ethylene glycol assured the functional enhancement of the electrodes, as demonstrated via an electrical and electrochemical characterization. A surface modification of the electrodes was carried out, based on voltammetric electropolymerization, to obtain a thin layer of polyaniline. The mechanism for pH sensing is based on the redox reactions of the polyaniline layer caused by protonation. The sensing performance of the microsystem was finally validated by monitoring its potentiometric response upon exposure to a relevant range of pH, Micro and Nano Engineering

The authors present a scheme intended for production of large quantities of lab on chip systems by means of Si dry etching, electroplating, injection molding, and pressure-assisted thermal bonding. This scheme allows for the fabrication of large numbers of samples having a combination of structures with depths as small as tens of nanometers and as big as hundreds of microns on the same polymer chip. The authors also describe in detail the fabrication procedure of polymer substrates with embedded Au and pedot:tosylate electrodes for electrochemical applications. The electrode fabrication process is simple and fit for integration in a production scheme. The electrode–substrates are then bonded to injection molded counterparts to be used for electrochemical applications. A dimensional and functional characterization of the electrodes is also presented here.

In this paper, we demonstrate recordings of the ion channel activity across the cell membrane in a biological cell by employing the so-called patch clamping technique on an injection-molded polymer microfluidic device. The findings will allow direct recordings of ion channel activity to be made using the cheapest materials and production platform to date and with the potential for very high throughput. The employment of cornered apertures for cell capture allowed the fabrication of devices without through holes and via a scheme comprising master origination by dry etching in a silicon substrate, electroplating in nickel and injection molding of the final part. The most critical device parameters were identified as the length of the patching capillary and the very low surface roughness on the inside of the capillary. The cross-sectional shape of the orifice was found to be less critical, as both rectangular and semicircular profiles seemed to have almost the same ability to form tight seals with cells with negligible leak currents. The devices were functionally tested using human embryonic kidney cells expressing voltage-gated sodium channels (Nav1.7) and benchmarked against a commercial state-of-the-art system for automated ion channel recordings. These experiments considered current–voltage (IV) relationships for activation and inactivation of the Nav1.7 channels and their sensitivity to a local anesthetic, lidocaine. Both IVs and lidocaine dose–response curves obtained from the injection-molded polymer device were in good agreement with data obtained from the commercial system.

I denne afhandling demonstreres højkvalitets målinger af ionkanalaktiviteten igennem cellemembranen i en biologisk celle ved anvendelse af den såkaldte "patch clamp" teknik på en sprøjtestøbt polymer mikrofluid chip. Sådanne målinger udføres traditionelt ved hjælp mikropipetter af glas, eller i de seneste år ved hjælp meget dyre microfluide chips til engangsbrug. Patch clamping metoden anvendes til både grundlæggende elektrofysiologiske studier på levende celler og i cellevæv og til "drug discovery". Resultaterne af dette arbejde vil gøre det muligt at direkte målinger af ionkanalaktivitet kan foretages på den billigste materiale- og produktionsplatform til dato, og med potentiale for meget højt throughput. Valget af et chip-design med brug af sidekanaler til indgangning af cellerne tillod at chips kunne fremstilles uden gennemgående huller og ved hjælp af en proces bestående af master-fremstilling ved brug af tør-æts i et silicium substrat, elektroplattering af en nikkel støbeform fra siliciummasteren, og endeligt sprøjtestøbning af plastikchips ved brug af nikkelformen. En grundig karakterisering af de kritiske mikrokanallysninger blev udført ved hjælp af SEM og AFM og viste høj replikationsnøjagtighed i hele produktionsprocessen. De mest kritiske chipparametre blev identificeret som længden af de kapillære sidekanaler til patching af cellerne og den meget lave overfladeruhed på indersiden af disse kaneler. Profilen af sidekanalerne fandtes at være mindre kritisk, da lysninger med forskellige profiler testet med celler viste den samme evne til at danne tætte forseglinger mod cellerne med ubetydelige lækstrømme. Evnen til at danne forsejlinger med høj elektrisk lækmodstand i omegnen af GOhm, de såkaldte "gigaseals", påvistes med en succesrate på 15%. Chips blev testet funktionelt med humane embryonale nyreceller (HEK), som udtrykte spændingsafhængige natriumkanaler og blev sammenlignet med et kommercielt state-of-the-art system til automatiserede ionkanalmå, In this thesis we demonstrate high quality recordings of the ion channel activity across the cell membrane in a biological cell by employing the so called patch clamping technique on an injection molded polymer microfluidic device. Such recordings are traditionally made using glass micropipettes, or in recent years using consumable microfluidic chips of high costs. The patch clamping method is widely used both in fundamental studies of electrophysiology of living cells and tissue and in drug discovery. The findings of this work will allow direct recordings of ion channel activity to be made using the cheapest materials and production platform to date, and with the potential for very high throughput. The employment of cornered apertures for cell capture allowed the fabrication of devices without through holes via a process comprising master origination by dry etching in a silicon substrate, electroplating in nickel, and injection molding of the final part. A thorough characterization of the patching orifices by means of SEM and AFM showed high replication accuracy through the fabrication process. The most critical device parameters were identified as the length of the patching capillaries and the very low surface roughness inside of the capillaries. The cross-sectional shape of the cornered apertures was found to be less critical, as apertures with different profiles were tested with cells and showed the same ability to form tight seals with cells with negligible leak currents. The ability to form high resistance seals in the GOhm range, the so called gigaseals, is demonstrated with a success rate of 15%. The devices were functionally tested with Human Embryonice Kidney (HEK) cells expressing voltage-gated sodium channels and benchmarked against a commercial state-of-the-art system for automated ion channel recordings. These experiments considered current-voltage relationships for activation and inactivation of the sodium channels and their sensitivity to a l

We present the fabrication of PEDOT and pyrolyzed micro-electrodes for the detection of neurotransmitter exocytosis from single cells. The patterns of the electrodes are defined with photolithography. The micro-electro-fluidic-chips were fabricated by bonding two injection molded TOPAS parts. Polymer electrodes integrated in polymer chips open the way for batch and low cost device fabrication.

We present a novel method to fabricate an all in polymer injection molded chip for electrochemical cell recordings and lateral cell trapping. The complete device is molded in thermoplastic polymer and it results from assembling two halves. We tested spin-coated conductive polymer poly(3,4-ethylenedioxythiopene) and showed that it can be used as an electrode material for detecting neurotransmitters electrochemically in biosensors.