# US 7,607,753 B2 · Liquid droplet forming method and liquid droplet forming device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,607,753 B2 - Document ID: US7607753B2 - Status: Granted - Kind: B2 - Application number: 11/660,350 - Filed: 2005-08-12 - Published: 2007-11-29 - Granted: 2009-10-27 - Earliest claimed: 2004-08-20 - Assignees: Hamamatsu Photonics K.K. - Inventors: Osamu Yogi; Tomonori Kawakami - Web page: https://patentgrep.com/patent/US7607753B2 ## CPC - B01L 3/0268: {using pulse dispensing or spraying, eg. inkjet type, piezo actuated ejection of droplets from capillaries} - B05B 5/025: Discharge apparatus, e.g. electrostatic spray guns - B05B 5/10: Arrangements for supplying power, e.g. charging power (in discharge apparatus B05B5/053) - B41J 2/06: by electric or magnetic field - B01L 2200/143: Quality control, feedback systems - B01L 2400/027: electrostatic forces between substrate and tip - B01L: CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE - B05B: SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES (spray-mixers with nozzles B01F25/72; processes for applying liquids or other fluent materials to surfaces by spraying B05D) - B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS ## Abstract A droplet forming method, for forming a droplet 27, constituted of a sample liquid 21, on a substrate 5 by applying a pulse voltage P between the sample liquid 21, retained in a nozzle 3, and the substrate 5, disposed opposite a tip of the nozzle 3, to discharge the sample liquid 21 from the tip of the nozzle 3, includes: a waveform measuring step S1 of measuring a temporal waveform of a current I that flows between the sample liquid 21 in the nozzle 3 and the substrate 5; and an application condition determining step S2 of determining, based on the temporal waveform of the current I, an application condition of the pulse voltage P during the forming of the droplet 27 on the substrate 5. ## Claims ### Claim 1 A droplet forming method comprising: a droplet forming step of applying a pulse voltage between a liquid retained in a nozzle, and a substrate disposed opposite a tip of the nozzle, to discharge the liquid retained inside the nozzle from the tip of the nozzle and form a droplet on the substrate; a waveform measuring step of measuring, in the droplet forming step, a temporal waveform of a current that flows between the liquid retained in the nozzle and the substrate; and an application condition determining step of determining an application condition of the pulse voltage in the droplet forming step based on the temporal waveform of the current measured in the waveform measuring step. ### Claim 2 (depends on 1) The droplet forming method according to claim 1, wherein the application condition of the pulse voltage, determined in the application condition determining step, includes at least one of a distance between the tip of the nozzle and the substrate, a pulse height of the pulse voltage, and a time width of the pulse voltage. ### Claim 3 (depends on 1) The droplet forming method according to claim 1, wherein in the application condition determining step, the application condition of the pulse voltage is determined based on an occurrence frequency of current pulse waveforms contained in the temporal waveform of the measured current. ### Claim 4 (depends on 1) The droplet forming method according to claim 1, wherein in the application condition determining step, the application condition of the pulse voltage is determined based on a pulse height of current pulse waveforms contained in the temporal waveform of the measured current. ### Claim 5 (depends on 1) The droplet forming method according to claim 1, further comprising: a volume measuring step of measuring a volume of the droplet based on an integration value of the temporal waveform of the current measured in the waveform measuring step. ### Claim 6 (depends on 1) The droplet forming method according to claim 1, wherein the liquid retained in the nozzle is a particle suspension, and the method further comprising: a particle number measuring step of measuring a number of particles contained in the droplet based on the temporal waveform of the measured current. ### Claim 7 (depends on 6) The droplet forming method according to claim 6, wherein in the particle number measuring step, the number of particles contained in the droplet is calculated based on a number of current pulse waveforms, which have a pulse width longer than a predetermined value among current pulse waveforms contained in the temporal waveform of the measured current. ### Claim 8 A droplet forming device comprising: a nozzle, retaining a liquid; a platform, on which a substrate is set at a position opposing a tip of the nozzle; a voltage applying means, applying a pulse voltage between the liquid retained in the nozzle, and the substrate; and a current measuring means, measuring a temporal waveform of a current, which flows between the liquid retained in the nozzle and the substrate according to the applied pulse voltage. ### Claim 9 (depends on 8) The droplet forming device according to claim 8, further comprising: a moving means that varies a relative position of the tip of the nozzle and the substrate. ### Claim 10 (depends on 8) The droplet forming device according to claim 8, further comprising: an application voltage determining means that determines on the basis of the temporal waveform of the current measured by the current measuring means, an application condition of the pulse voltage applied by the voltage applying means in a process of forming a droplet on the substrate. ### Claim 11 (depends on 8) The droplet forming device according to claim 8, further comprising: an analyzing means, analyzing the temporal waveform of the current measured by the current measuring means and determining at least one of an occurrence frequency and a pulse height of current pulse waveforms contained in the temporal waveform. ### Claim 12 (depends on 11) The droplet forming device according to claim 11, further comprising: an application voltage determining means that determines, on the basis of an analysis result of the analyzing means, an application condition of the pulse voltage applied by the voltage applying means in a process of forming a droplet on the substrate.