Aspiration device for determining mechanical properties of soft tissues and methods therefor

An aspiration device for measuring the viscoelastic behaviour of biological tissues and synthetic materials, comprising:

• a probe head having the form of a cup with
• a cavity,
• side wall(s) and
• a top wall,
• a first probe channel connected to the probe head,
• a second probe channel connected to the probe head,
• a pressure unit providing a vacuum inside the first probe channel,
• a pressure sensor provided in the first probe channel for detecting the pressure in the first probe channel,
• a valve closing the second probe channel, and
• a control unit connected to the pressure unit for controlling the pressure unit and connected to the valve for controlling the valve,
• wherein the first probe channel has a distal end leading with its lower open end through the top wall into the cavity of the probe head,
• wherein the control unit is configured to execute a measurement cycle comprising applying under pressure in the first probe channel, measuring the under pressure with the pressure sensor, detecting a change of under pressure increase over time, increasing the under pressure to a predetermined maximum under pressure, decreasing the under pressure beyond this point in time and detecting a change of under pressure decrease over time, and
• wherein the control unit is configured to calculate from the pressure values received and time values measured output values from the group comprising the closing pressure value pclose and closing time value tclose at the change of under pressure increase over time, the opening pressure value popen and opening time value topen at the change of under pressure decrease over time as well as the tissue stiffness and the release ratio
• r
• ⁢
• r
• =
• p
• open
• p
• close
• .

An aspiration device for measuring the viscoelastic behaviour of biological tissues and synthetic materials, comprising:

• a probe head having the form of a cup with
• a cavity,
• side wall(s) and
• a top wall,
• a first probe channel connected to the probe head and having a first open end,
• a third probe channel connected to the probe head and having a third open end,
• a pressure unit providing a vacuum inside the third probe channel,
• a pressure sensor provided in the first probe channel for detecting the pressure in the first probe channel,
• a control unit connected to the pressure unit for controlling the pressure unit,
• wherein the first probe channel has a distal end leading with its first open end through the top wall into the cavity of the probe head,
• wherein the third open end is positioned nearer to the top wall than the first open end,
• wherein the control unit is configured to execute a measurement cycle comprising applying under pressure in the third probe channel, measuring the under pressure with the pressure sensor, detecting a change of under pressure increase over time, increasing the under pressure to a predetermined maximum under pressure, decreasing the under pressure beyond this point in time and detecting a change of under pressure decrease over time, and
• wherein the control unit is configured to calculate from the pressure values received and time values measured output values from the group comprising the closing pressure value pclose and closing time value tclose at the change of under pressure increase over time, the opening pressure value popen and opening time value topen at the change of under pressure decrease over time as well as the tissue stiffness and the release ratio
• r
• ⁢
• r
• =
• p
• open
• p
• close
• .

A method for measuring the viscoelastic deformability of biological tissues and synthetic materials from the group encompassing tissues to be tested in-vivo:

• skin and mucous membranes of humans or animals, especially directly reachable surfaces inside the mouth, nose, vagina, cervix;
• tissues and materials to be tested ex-vivo and in-vitro:
• compliant elastomers or other synthetic materials, hydrogels, tissue engineering scaffolds, decellularized extracellular matrix, cellulose based materials, organotypic in-vitro systems, or soft implants, especially breast implant bodies or meshes with closed mainly impermeable surfaces, as well as tissues and tissue materials and materials to be tested in-vivo and ex-vivo:
• artificial skin or skin substitute by
• making available an aspiration apparatus having
• a probe head having the form of a cup with a cavity, one or more side walls and a top wall,
• a first probe channel connected to the probe head,
• a pressure unit providing a vacuum inside the first probe channel,
• a pressure sensor provided in the first probe channel for detecting the pressure in the first probe channel, and
• a control unit connected to the pressure unit for controlling the pressure unit,
• wherein the first probe channel has a distal end leading with its lower open end through the top wall into the cavity of the probe head and wherein the cavity comprises an opening in the side or in the top wall,
• contacting the probe head with the biological tissue or synthetic material,
• applying an under pressure on the biological tissue or material via the first probe channel in the cavity,
• increasing, in the cavity, the under pressure to a predetermined maximum under pressure,
• decreasing the under pressure beyond the point in time when the predetermined maximum under pressure is reached, and
• detecting a change of under pressure decrease over time,
• determining by the control unit at least one output value from the group comprising the closing pressure value pclose when the biological tissue or synthetic material closes the first probe channel during under pressure increase, the closing time value tclose when the biological tissue or synthetic material closes the first probe channel during under pressure increase, the opening pressure value popen when the biological tissue or synthetic material re-opens the first probe channel during under pressure decrease, the opening time value topen when the biological tissue or synthetic material re-opens the first probe channel during under pressure decrease, wherein one or both of the closing pressure value pclose and the closing time value tclose are determined based on the different slope of the under pressure increase when the biological tissue or synthetic material closes the first probe channel during under pressure increase.