Electrode for whole cell and other testing
A pushpen electrode is provided for electrophysiology measurements. The pushpen operation is used to impale a cell membrane in cell-attached configuration to go whole-cell without disruption of the gigaseal. The pushpen electrode has advantages over the conventional patch clamp electrode in reducing tip series resistance, increasing signal bandwidth, permitting longer-term recordings and reducing diffusion between the cytosol and the electrode solution.
1. An electrode comprising a pipette having an open tip, a transducer on a carrier assembly disposed for movement in the pipette, and an actuator configured to move the carrier assembly in the pipette, wherein the carrier assembly comprises an inner protrudable member movable in the pipette by the actuator and on which protrudable member the transducer comprising a silver wire coated with AgCl is wound and insulated by an insulating tube disposed around the protrudable member therebetween, wherein the transducer on the insulating tube moves with the inner protrudable member in the pipette, and wherein the inner protrudable member has a pointed end movable past and outside the pipette open tip to a controlled testing position.
2. The electrode of claim 1 wherein the transducer comprises a single silver wire coated with AgCl and wherein the protrudable member has a pointed end movable past and outside of the pipette open tip to the controlled testing position.
3. The electrode of claim 2 wherein the protrudable member has a pointed wire end that is movable past and outside the pipette open tip to the controlled testing position.
4. The electrode of claim 1 wherein the protrudable member comprises a pointed end rod or pointed end tube.
5. The electrode of claim 1 wherein the protrudable member is a voltage-transducing metallic member.
6. The electrode of claim 1 wherein the actuator comprises an electrical actuator or other linear actuator.
7. The electrode of claim 1 wherein the actuator comprises a hydraulic actuator.