CN109203451B

CN109203451B - Novel biological printing method based on air flow transmission

Info

Publication number: CN109203451B
Application number: CN201811041478.3A
Authority: CN
Inventors: 张彦振; 李德格; 刘永红
Original assignee: China University of Petroleum East China
Current assignee: China University of Petroleum East China
Priority date: 2018-09-07
Filing date: 2018-09-07
Publication date: 2021-02-02
Anticipated expiration: 2038-09-07
Also published as: CN109203451A

Abstract

The invention relates to a new printing method based on an airflow transmission technology, and belongs to the technical field of microfluid and biological printing. The printing method based on the airflow transmission technology continuously extrudes ink from a micro-channel, and the surface of the outlet of the micro-channel is a super-hydrophobic surface; and applying a stream of air flow in the direction towards the printing surface while extruding the ink to blow the air flow through the liquid drops at the outlet of the micro-channel. As the volume of the droplets increases, the force exerted on them by the air flow increases, eventually blowing the droplets off the outlet and onto the printing surface. Besides the open type super-hydrophobic surface, the method can also adopt a closed airflow channel with a super-hydrophobic inner wall as a channel for generating and conveying liquid drops. The confinement effect of the closed airflow channel on the airflow is more favorable for controlling the trajectory and the drop point of the liquid drops. The size of the liquid drop can be regulated and controlled by the size of the liquid outlet hole, the injection flow of ink, the size of air flow and the hydrophilicity and hydrophobicity of the surface where the liquid outlet hole is located.

Description

Novel biological printing method based on air flow transmission

Technical Field

The invention belongs to the technical field of microfluid and biological printing, and relates to a novel method for generating, transmitting and printing liquid drops based on an airflow transmission technology.

Technical Field

According to different biological ink ejection modes, the current biological 3D printing technology mainly adopts two types of nozzles. One is to continuously squeeze the bio-ink out of a fine orifice on the head using pressure. This mode of operation requires a certain pressure to be applied to the bio-ink and the distance between the nozzle and the organism to be printed must be kept very small during the printing process. Another is to use a conventional inkjet printhead to break up the bio-ink into individual droplets that are ejected from an orifice. Conventional inkjet print heads can be largely classified into two types, piezoelectric type heads and thermal bubble type heads, according to the driving method. The working principle of the piezoelectric type spray head is as follows: the micro-pressure electric driving device is quickly deformed under the action of an electric signal to quickly extrude the ink storage cavity, so that the ink is quickly sprayed out from the spray head to form discrete liquid drops with a certain initial speed to fly to the printing surface. For the thermal foaming type nozzle, a heating device capable of quickly converting an electric signal into a thermal signal is arranged in the liquid storage cavity, ink contacting with the heating device can be quickly vaporized to form quickly expanded bubbles, and the pressure in the liquid storage cavity is quickly increased by the bubbles, so that the ink is sprayed out from the spray hole.

Regardless of the piezoelectric or thermal bubble type of the inkjet head, the ink in the reservoir undergoes a pressure shock every time a droplet is ejected. This pressure can typically reach several atmospheres, and therefore tends to cause some mechanical damage to the printed bioactive substances, such as cells. For thermal bubble nozzles, the ink also needs to be subjected to thermal shock, which is likely to cause damage to the active substances in the bio-ink. In addition, since the micro flow channels and the orifice size inside the conventional inkjet printing head are relatively small, head clogging often occurs, especially when printing bio-ink containing cells.

Disclosure of Invention

The invention aims to provide a novel printing method based on an air flow conveying technology, which is suitable for biological printing, and is particularly suitable for printing cell solution. It is also suitable for printing with common ink.

The principle of the invention is as follows: the invented printing method based on air flow transmission technology is to continuously extrude ink from small holes on a super-hydrophobic surface; a beam of air flow blowing to the printing surface is arranged above the small hole. With the increasing of the volume of the liquid drop, the windward area of the liquid drop is also increased, and the shearing force applied to the air flow and parallel to the surface of the liquid drop is also increased. When the shearing force is larger than the adhesive force of the liquid drop on the surface, the liquid drop falls off from the surface and is conveyed to the printing surface by the air flow, and the printing is finished.

The invention has the following advantages:

1 the liquid drop generating process has no pressure impact, thermal shock, strong electric/magnetic field and the like harmful to the biological active substances, and is very suitable for printing other biological active substances including cells and the like.

2. The size of liquid drop and printing frequency can be regulated and controlled by the size of liquid outlet hole, ink injection flow rate and air flow speed.

3. The operation is simple and convenient, and the requirement on equipment is low.

Drawings

Fig. 1 is a schematic view of the printing principle based on the air flow transport technique in the case of an open surface.

Fig. 2 is a schematic diagram of the printing principle based on the air flow transmission technology in the micro-channel.

FIG. 3 is a schematic diagram of a droplet generation process.

FIG. 4 is a schematic diagram of the principle of simultaneous printing of multiple inks in a microchannel based on air flow transport technology.

Detailed Description

See fig. 1. The invention relates to a novel printing method based on an air flow transmission technology, in particular to a method for extruding ink from an outlet of a micro-channel to form liquid drops attached to the surface of the outlet. The size of the outlet of the micro-channel is generally ten micrometers to hundreds of micrometers, and the surface on which the micro-channel is arranged is a super-hydrophobic surface. And applying an air flow in a direction towards the printing surface while extruding the ink to blow the ink through the liquid drops, wherein the action force of the air flow on the liquid drops is increased along with the increase of the volume of the liquid drops, and finally the liquid drops are blown off from the outlet and are conveyed to the printing surface. In addition to using an open superhydrophobic surface, droplet generation and transport can also occur inside a closed gas flow channel, see fig. 2. And a closed airflow channel is adopted, so that the control on the flying track and the landing point of the liquid drop is facilitated. The volume increasing process and the blowing process of the droplets are shown in fig. 3.

When ink is continuously injected, a printing operation can be performed at a certain frequency. The ink injection is stopped, i.e., the printing can be stopped. It is also possible to inject a metered volume of ink to achieve a single or specified drop number print job.

When a closed airflow channel is adopted, two or more ink channels can be adopted at the same time, so that the simultaneous printing of different inks is realized, and the method is shown in fig. 4.

The method also supports the simultaneous use of multiple parallel gas flow channels to improve printing efficiency.

Claims

1. A new biological printing method based on air flow transmission is characterized in that: continuously and stably extruding the ink from the small holes on the super-hydrophobic surface, and simultaneously applying a continuous and stable airflow which is blown to the printing surface above the extruded liquid drops; the acting force of the air flow on the liquid drops is increased along with the increase of the volume of the liquid drops and also increased along with the increase of the strength of the air flow; when the volume of the liquid drops is increased to a certain value, the acting force of the air flow on the liquid drops enables the liquid drops to be separated from the liquid outlet holes and the super-hydrophobic surfaces where the liquid outlet holes are located softly, and finally the liquid drops are conveyed to the printing surface by the air flow to finish printing; the size of liquid drop and printing frequency can be regulated and controlled by the size of liquid outlet hole, ink injection flow rate and air flow speed.

2. The new method for bioprinting based on air flow delivery as claimed in claim 1, wherein: the surface of the liquid outlet hole can be an open surface or the inner surface of a closed airflow channel; when the closed airflow channel is adopted, two or more ink channels are adopted, and the simultaneous printing of different inks is realized.