Automated blood sampling device

Abstract

Devices are provided to automatically access blood from beneath or within skin. These devices include an injector configured to drive a needle into the skin and subsequently to retract the needle from the skin. These devices additionally include a seal to which suction is applied. To drive the needle into the skin, the needle is first driven through the seal, creating at least one hole in the seal. The suction applied to the seal acts to draw blood from the puncture formed in the skin by the needle, through the at least one hole in the seal, and to a sensor, blood storage element, or other payload. These devices can be wearable and configured to automatically access blood from skin, for example, to access blood from the skin at one or more points in time while a wearer of a device is sleeping.

What is claimed is: 
     
         1 . A system comprising:
 a needle, wherein the needle is configured to penetrate skin;   an injector, wherein the injector is configured to drive the needle into the skin to form a puncture in the skin and subsequently to retract the needle from the skin;   a sensor, wherein the sensor is configured to detect a property of blood to which the sensor is exposed; and   a controller configured to:
 operate the injector to drive the needle into the skin; and 
 subsequent to operating the injector to drive the needle into the skin, operate the sensor to detect a property of blood received from the skin in response to the needle being driven into the skin. 
   
     
     
         2 . The system of  claim 1 , wherein the system comprises a body-mountable device, wherein the body-mountable device is configured to be mounted to a surface of the skin, and wherein the controller is configured to operate the injector to drive the needle into the skin at a specified point in time. 
     
     
         3 . The system of  claim 2 , wherein the needle, injector, and sensor are disposed in a first sampling section of the body-mountable device, and wherein the body-mountable device further comprises one or more additional sampling sections, each additional sampling section including a respective needle, injector, and sensor. 
     
     
         4 . The system of  claim 3 , wherein the controller is configured to operate an injector of a particular additional sampling section to drive a needle of the additional sampling section into the skin at a further specified point in time. 
     
     
         5 . The system of  claim 1 , wherein the injector comprises:
 a chamber, wherein the needle is disposed at least partially within the chamber;   a piston disposed in the chamber, wherein the needle is coupled to the piston, and wherein the piston is configured to slidably move within the chamber; and   a propellant, wherein the propellant is configured to slidably move the piston within the chamber to drive the needle into skin.   
     
     
         6 . The system of  claim 5 , wherein the propellant comprises nitrocellulose, and wherein the injector driving the needle into skin comprises the injector igniting the nitrocellulose. 
     
     
         7 . The system of  claim 5 , wherein the injector driving the needle into skin comprises the injector igniting the propellant using a resistive heating element. 
     
     
         8 . The system of  claim 5 , wherein the injector includes at least one vent, wherein the vent is configured to allow the propellant to vent out of the injector such that the piston and needle can retract from the skin subsequent to the needle being driven into the skin. 
     
     
         9 . The system of  claim 1 , further comprising:
 a suction source configured to provide suction; and   a seal, wherein the seal is configured to receive suction provided by the suction source, wherein the injector is configured to drive the needle through the seal to form at least one hole in the seal, and wherein the suction provided by the suction source is configured to draw blood from the formed puncture in the skin through the formed at least one hole in the seal.   
     
     
         10 . The system of  claim 9 , further comprising at least one further needle, wherein the injector is configured to drive the at least one further needle into the skin to form at least one further puncture in the skin and subsequently to retract the at least one further needle from the skin, and wherein the injector is configured to drive the at least one further needle through the seal to form at least one further hole in the seal. 
     
     
         11 . The system of  claim 9 , wherein the seal comprises a concave depression, wherein the injector is configured to drive the needle through the concave depression of the seal to form at least one hole in the seal, and wherein the suction provided by the suction source is configured to suction the skin into the concave depression. 
     
     
         12 . The system of  claim 9 , wherein the suction source comprises an evacuated volume having a pressure less than approximately 50 kilopascal. 
     
     
         13 . The system of  claim 9 , further comprising a blood storage element, wherein the suction provided by the suction source is configured to draw blood through the formed at least one hole in the seal to the blood storage element, and wherein the blood storage element is configured to store blood drawn by the suction to the blood storage element. 
     
     
         14 . The system of  claim 9 , wherein the suction provided by the suction source is configured to draw blood through the formed at least one hole in the seal to the sensor. 
     
     
         15 . The system of  claim 9 , further comprising a conformal layer, wherein the conformal layer is configured to conform to the skin such that the suction provided by the suction source through the formed at least one hole in the seal applies suction to the skin proximate the at least one hole in the seal. 
     
     
         16 . A method comprising:
 mounting a system to skin, wherein the system comprises:
 a needle, wherein the needle is configured to penetrate the skin, 
 an injector, wherein the injector is configured to drive the needle into the skin to form a puncture in the skin and subsequently to retract the needle from the skin; and 
 a sensor, wherein the sensor is configured to detect a property of blood to which the sensor is exposed; 
   operating the injector to drive the needle into the skin to form a puncture in the skin and subsequently to retract the needle from the skin; and   operate the sensor to detect a property of blood received from the skin in response to the needle being driven into the skin.   
     
     
         17 . The method of  claim 16 , wherein the system further comprises a suction source configured to provide suction, wherein the suction provided by the suction source is configured to draw blood from the formed puncture in the skin to the sensor. 
     
     
         18 . The method of  claim 16 , wherein the injector comprises:
 (a) a chamber, wherein the needle is disposed at least partially within the chamber,   (b) a piston disposed in the chamber, wherein the needle is coupled to the piston, and wherein the piston is configured to slidably move within the chamber, and   (c) a propellant, wherein the propellant is configured to slidably move the piston within the chamber to drive the needle into skin,   wherein operating the injector to drive the needle into the skin comprises igniting the propellant.   
     
     
         19 . The method of  claim 16 , wherein the system comprises a body-mountable device, wherein the body-mountable device is configured to be mounted to a surface of the skin, wherein the system further comprises a controller that is operably coupled to the sensor and the injector, wherein operating the injector to drive the needle into the skin to form a puncture in the skin and subsequently to retract the needle from the skin comprises the controller operating the injector to drive the needle into the skin at a specified point in time, and wherein operating the sensor to detect a property of blood comprises the controller operating the sensor to detect the property of blood subsequent to the specified point in time. 
     
     
         20 . The method of  claim 19 , wherein the needle, injector, and sensor are disposed in a first sampling section of the body-mountable device, and wherein the body-mountable device further comprises an additional sampling section comprising an additional needle, an additional injector, and an additional sensor, and wherein the controller is configured to:
 operate the additional injector, at an additional specified point in time, to drive the additional needle into the skin to form an additional puncture in the skin and subsequently to retract the additional needle from the skin; and   operate the additional sensor to detect a property of blood received from the skin in response to the additional needle being driven into the skin.