Apparatus and Method for Electrically Contacting Biological Cells Suspended in a Liquid

Abstract

An apparatus for electrically contacting biological cells suspended in a liquid has a substrate having at least one opening and an electrode for electrically contacting a cell immobilized above the opening. A contact unit with a contact tip is arranged below said opening. A top end of the contact tip projects into the opening in such a way that it comes to bear against a cell membrane of the immobilized cell. The contact tip has a contact channel which ends at its top end. A hydrodynamic low pressure can be exerted upon the cell membrane via the contact channel, and the electrode is electrically connected to the contact channel. In a method for electrically contacting biological cells suspended in a liquid, a cell is immobilized above an opening provided in a substrate, and the immobilized cell is contacted via at least one electrode. For contacting the immobilized cell, a hydrodynamic low pressure is generated acting on a cell membrane through a contact tip projecting into the opening.

1 . An apparatus for electrically contacting biological cells suspended in a liquid, said apparatus comprising:
 a substrate having at least one opening,   a suction channel ending in said opening, said suction channel being adapted to provide a first hydrodynamic low pressure at the opening for immobilizing a cell having a cell membrane on top of said opening,   a contact unit being arranged below the opening and comprising a contact tip, and   at least one electrode for electrically contacting the cell when it is immobilized on said opening,   wherein the contact tip comprises a top end projecting into said opening in such a way that said contact tip comes to bear against the cell membrane when the cell is immobilized on top of said opening, and further comprises a contact channel which opens at the top end in such a way that a second hydrodynamic low pressure can be exerted upon the cell membrane to provide for a gigaseal between the contact tip and the cell membrane, and   wherein the electrode is arranged within said contact channel.   
     
     
         2 . The apparatus of  claim 1 , wherein the contact unit is detachably arranged at said substrate. 
     
     
         3 . The apparatus of  claim 2 , wherein the contact tip is replaceably arranged within said contact unit. 
     
     
         4 . The apparatus of  claim 1 , wherein the suction channel extends inside the substrate. 
     
     
         5 . The apparatus of  claim 1 , wherein the suction channel comprises at least one section extending inside the contact unit. 
     
     
         6 . The apparatus of  claim 1 , wherein the contact unit rests against the substrate in a region of said opening, thereby sealing said opening in a liquid-tight manner. 
     
     
         7 . The apparatus of  claim 1 , wherein the contact unit has a replaceable top part comprising the contact tip and a reusable bottom part comprising the electrode and a first section of the contact channel. 
     
     
         8 . The apparatus of  claim 7 , wherein the top part rests under pressure against the substrate and wherein the bottom part rests under pressure against the top part. 
     
     
         9 . The apparatus of  claim 8 , further comprising a sealant provided between at least one of the substrate and the top part or the top part and the bottom part. 
     
     
         10 . The apparatus of  claim 10 , wherein the sealant is selected from the group of: silicone paste, two-component elastomer, polydimethylsiloxane elastomer. 
     
     
         11 . The apparatus of  claim 7 , further comprising a chamber provided in the bottom part, with the electrode projecting into said chamber and with said first section leading into said chamber, and with said contact channel further comprising a second section located in the top part and being connected to said chamber. 
     
     
         12 . The apparatus of  claim 11 , wherein the second section is funnel-shaped and extends through the contact tip. 
     
     
         13 . An apparatus for electrically contacting biological cells suspended in a liquid, said apparatus comprising:
 a substrate having at least one opening,   a suction channel ending in said opening, said suction channel being adapted to provide a first hydrodynamic low pressure at the opening for immobilizing a cell having a cell membrane on said opening,   a contact unit being arranged below the opening and comprising a contact tip, and   at least one electrode for electrically contacting the cell when it is immobilized on said opening,   wherein the contact tip comprises a top end projecting into said opening in such a way that said contact tip comes to bear against the cell membrane when the cell is immobilized on said opening, and further comprises a contact channel which opens at the top end in such a way that a second hydrodynamic low pressure can be exerted upon the cell membrane, and   wherein the electrode is arranged within said contact channel, and   wherein the contact unit has a replaceable top part comprising the contact tip and a reusable bottom part comprising the electrode and a first section of the contact channel,   wherein the top part further comprises an annular recess formed around the contact tip and facing the substrate, with the annular recess having a passage connected to the suction channel, and   wherein the annular recess is covered by a membrane having a gap which surrounds the contact tip at a distance.   
     
     
         14 . The apparatus of claim  38 , wherein the membrane is fixed to the top part. 
     
     
         15 . An apparatus for electrically contacting biological cells suspended in a liquid, said apparatus comprising:
 a substrate having at least one opening,   a suction channel ending in said opening, said suction channel being adapted to provide a first hydrodynamic low pressure at the opening for immobilizing a cell having a cell membrane on top of said opening,   a contact unit being arranged below the opening and comprising a contact tip, and   at least one electrode for electrically contacting the cell when it is immobilized on said opening,   wherein the contact tip comprises a top end projecting into said opening in such a way that said contact tip comes to bear against the cell membrane and exerts a contact pressure onto the cell membrane when the cell is immobilized on top of said opening, and further comprises a contact channel which opens at the top end in such a way that a second hydrodynamic low pressure can be exerted upon the cell membrane, and   wherein the electrode is arranged within said contact channel.