WO2020069060A1 - Thermally regulated window cassette for additive manufacturing apparatus - Google Patents

Abstract

A removable window cassette for a bottom-up stereolithography apparatus includes (a) a light-transmissive window having a rigid bottom portion and a semipermeable top portion, with the rigid bottom portion comprised of a thermally conductive material; (b) a circumferential frame surrounding the window and into which the window is recessed, the frame having a top portion, a bottom portion, and an internal wall portion, the frame internal wall portion defining with the window semipermeable top portion a well into which a polymerizable liquid may be received; and (c) at least one thermoelectric device in the circumferential frame and in thermal contact with the rigid bottom portion.

Description

THERMALLY REGULATED WINDOW CASSETTE FOR ADDITIVE

MANUFACTURING APPARATUS

RELATED APPLICATIONS

[0001] This applications claims priority to U.S. Provisional Application Serial No. 62/738,061, filed September 28, 2018, the disclosure of which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

[0002] The present invention concerns additive manufacturing in general, and particularly concerns streolithography-type additive manufacturing.

BACKGROUND OF THE INVENTION

[0003] A group of additive manufacturing techniques sometimes referred to as "stereolithography" create a three-dimensional object by the sequential polymerization of a light polymerizable resin. Such techniques include "bottom-up" techniques, where light is projected into the resin through a light-transmissive“window” onto the bottom of the growing object, which object is carried up and out of the resin pool on a“build platform.”

[0004] The recent introduction of a more rapid stereolithography technique sometimes referred to as continuous liquid interface production (CLIP) has expanded the usefulness of stereolithography from prototyping to manufacturing. See J. Tumbleston, D. Shirvanyants, N. Ermoshkin et al., Continuous liquid interface production of 3D objects, SCIENCE 347, 1349- 1352 (published online 16 March 2015); US Patent Nos. 9,211,678; 9,205,601; and 9,216,546 to DeSimone et al.; see also R. Janusziewicz, et al., Layerless fabrication with continuous liquid interface production, PNAS 113, 11703-11708 (18 Oct. 2016).

[0005] Dual cure resins for additive manufacturing were introduced shortly after the introduction of CLIP, expanding the usefulness of stereolithography for manufacturing a broad variety of objects still further. See Rolland et al., US Patent Nos. 9,676,963, 9,453,142 and 9,598,606; J. Poelma and J. Rolland, Rethinking digital manufacturing with polymers, SCIENCE 358, 1384-1385 (15 Dec. 2017).

[0006] The foregoing developments have in turn lead to a need for window cassettes that can be more rapidly exchanged in bottom-up additive manufacturing apparatus.

[0007] In addition, it has been recognized that stereolithography resins— both conventional and dual cure— can be viscous, that viscosity can limit the speeds of production otherwise attainable by CLIP, and that resins may be heated when necessary to reduce their viscosity. And conversely, due to the exothermic nature of some polymerization processes during additive manufacturing, it has been recognized that the resins may need to be cooled under certain operating conditions if higher speeds of production are to be maintained (see, e.g., US Patent Nos, 9,211,678; 9,205,601; and 9,216,546 to DeSimone et al.).

[0008] However, systems that provide for both the rapid exchange of window cassettes, and include heating and/or cooling thereof, have not heretofore been described.

SUMMARY OF THE INVENTION

[0009] A first aspect of the invention is a removable window cassette for a bottom-up stereolithography apparatus, including: (a) a light-transmissive window having a rigid bottom portion and a semipermeable top portion, with the rigid bottom portion comprised of a thermally conductive material; (b) a circumferential frame surrounding the window and into which the window is recessed, the frame having a top portion, a bottom portion, and an internal wall portion, the frame internal wall portion defining with the window semipermeable top portion a well into which a polymerizable liquid may be received; and (c) at least one thermoelectric device in the circumferential frame and in thermal contact with the rigid bottom portion.

[0010] In some embodiments, the at least one thermoelectric device comprises a plurality of thermoelectric devices.

[0011] In some embodiments, the at least one thermoelectric device comprises (i) at least one resistive heater, (ii) at least one Peltier device, or ( Hi ) both at least one resistive heater and at least one Peltier device.

[0012] In some embodiments, the rigid bottom portion is comprised of glass, sapphire, or transparent aluminum (ALON).

[0013] In some embodiments, the window semipermeable top portion is comprised of a fluoropolymer.

[0014] In some embodiments, the cassette further includes a fluid channel bed formed in said window between said bottom portion and said top portion, said channel bed having a first header, a second header, and a channel array therebetween, with said channel array configured to supply an inhibitor of polymerization through said semipermeable top portion; a first fluid inlet in said circumferential frame bottom portion, said first fluid inlet connected to said first channel bed header; and a second fluid inlet in said circumferential frame bottom portion, said second fluid inlet connected to said second channel bed header.

[0015] In some embodiments, the window top portion and the window bottom portion have opposing internal surfaces directly or indirectly adhered to one another, and in thermal contact with one another (e.g., through the entire surface area of the faces, except as interrupted by the channels of said fluid channel bed).

[0016] In some embodiments, the circumferential frame is rectangular.

[0017] In some embodiments, the window is generally flat and planar.

[0018] A second aspect of the invention is a bottom-up stereolithography apparatus, including: a removable window cassette as described above, and in further detail below; a carrier platform positioned above the window and configured for defining a build region between the semipermeable top portion and the carrier platform; a drive operatively associated with the carrier platform and the window and configured for advancing the window and the carrier platform away from one another; a light source positioned beneath the window; at least one temperature sensor operatively associated with the build region and configured to sense the temperature of a polymerizable resin in the build region; and a temperature controller operatively associated with the temperature sensor and the at least one thermoelectric device, the controller configured to activate the at least one thermoelectric device to maintain the temperature of a polymerizable resin in the build region above a predetermined minimum temperature and/or below a predetermined maximum temperature.

[0019] In some embodiments, the controller comprises a proportional-integral-derivative (PID) controller, a proportional integral (PI) controller, or a dynamic matrix controller (DMC).

[0020] In some embodiments, the at least one thermoelectric device and the controller are configured for both heating and cooling said resin.

[0021] In some embodiments, the temperature sensor includes a contact or non-contact temperature sensor operatively associated with the window.

[0022] In some embodiments, the apparatus further includes a fluid (e.g., an oxygen-enriched gas) supply system operatively associated with the first fluid inlet and the second fluid inlet (e.g., a fluid source operatively associated with said first inlet, and a vacuum source operatively associated with the second inlet). [0023] In some embodiments, the apparatus further includes a break-away electrical connector (e.g., a magnetic break-away connector) on the frame and electrically interconnecting the at least one thermoelectric device to the temperature controller.

[0024] The foregoing and other objects and aspects of the present invention are explained in greater detail in the drawings herein and the specification set forth below. The disclosures of all United States patent references cited herein are to be incorporated herein by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 is a schematic diagram of a first embodiment of a window cassette and stereolithography apparatus of the present invention, employing a plurality of heaters.

[0026] FIG. 2 is a top plan view of a window cassette of FIG. 1.

[0027] FIG. 3 is a schematic diagram of a second embodiment of a window cassette of the present invention, employing a plurality of Peltier coolers.

[0028] FIG. 4 is a top plan view of the window cassette of FIG. 3.

[0029] FIG. 5 is a schematic diagram of a third embodiment of a window cassette, and a portion of a stereolithography apparatus, of the present invention, again employing a plurality of Peltier coolers.

[0030] FIG. 6 is a top plan view of the window cassette of FIG. 5.

[0031] FIG. 7 is a schematic diagram of a fourth embodiment of a window cassette, and a portion of a stereolithography apparatus, of the present invention, again employing a plurality of Peltier coolers.

DETAILED DESCRIPTIONO F ILLUSTRATIVE EMBODIMENTS

[0032] The present invention is now described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art.

[0033] Like numbers refer to like elements throughout. In the figures, the thickness of certain lines, layers, components, elements or features may be exaggerated for clarity. Where used, broken lines illustrate optional features or operations unless specified otherwise.

[0034] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,”“an” and“the” are intended to include plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms“comprises” or“comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements components and/or groups or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups or combinations thereof.

[0035] As used herein, the term“and/or” includes any and all possible combinations or one or more of the associated listed items, as well as the lack of combinations when interpreted in the alternative ("or").

[0036] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and claims and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well- known functions or constructions may not be described in detail for brevity and/or clarity.

[0037] It will be understood that when an element is referred to as being“on,”“attached” to, “connected” to,“coupled” with,“contacting,” etc., another element, it can be directly on, attached to, connected to, coupled with and/or contacting the other element or intervening elements can also be present. In contrast, when an element is referred to as being, for example,“directly on,”“directly attached” to,“directly connected” to,“directly coupled” with or“directly contacting” another element, there are no intervening elements present. It will also be appreciated by those of skill in the art that references to a structure or feature that is disposed“adjacent” another feature can have portions that overlap or underlie the adjacent feature.

[0038] Spatially relative terms, such as“under,”“below,”“lower,”“over,”“upper” and the like, may be used herein for ease of description to describe an element’s or feature’s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, elements described as“under” or“beneath” other elements or features would then be oriented“over” the other elements or features. Thus the exemplary term“under” can encompass both an orientation of over and under. The device may otherwise be oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. Similarly, the terms“upwardly,” “downwardly,”“vertical,”“horizontal” and the like are used herein for the purpose of explanation only, unless specifically indicated otherwise.

[0039] It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. Rather, these terms are only used to distinguish one element, component, region, layer and/or section, from another element, component, region, layer and/or section. Thus, a first element, component, region, layer or section discussed herein could be termed a second element, component, region, layer or section without departing from the teachings of the present invention. The sequence of operations (or steps) is not limited to the order presented in the claims or figures unless specifically indicated otherwise.

[0040] 1. ADDITIVE MANUFACTURING APPARATUS.

[0041] Bottom up stereolithography techniques are known and described in, for example, U.S. Patent No. 5,236,637 to Hull, US Patent Nos. 5,391,072 and 5,529,473 to Lawton, U.S. Patent No. 7,438,846 to John, US Patent No. 7,892,474 to Shkolnik, U.S. Patent No. 8,110,135 to El-Siblani, U.S. Patent Application Publication No. 2013/0292862 to Joyce, and US Patent Application Publication No. 2013/0295212 to Chen et al. The disclosures of these patents and applications are incorporated by reference herein in their entirety.

[0042] In some embodiments, the object is formed by continuous liquid interface production (CLIP). CLIP is known and described in, for example, US Patent No. 9,211,678, US Patent No. 9,205,601, US Patent No 9,216,546, and in J. Tumbleston, D, Shirvanyants, N. Ermoshkin et al., Continuous liquid interface production of 3D Objects, Science 347, 1349- 1352 (published online 16 March 2015). See also R. Janusziewcz et al., Layerless fabrication with continuous liquid interface production, Proc. Natl. Acad. Sci. USA 113, 11703-11708 (October 18, 2016). Other approaches for carrying out CLIP that can be used in the present invention and potentially obviate the need for a semipermeable "window" or window structure include utilizing a liquid interface comprising an immiscible liquid (see L. Robeson et al., WO 2015/164234, published October 29, 2015), generating oxygen as an inhibitor by electrolysis (see I Craven et al., WO 2016/133759, published August 25, 2016), and incorporating magnetically positionable particles to which the photoactivator is coupled into the polymerizable liquid (see J. Rolland, WO 2016/145182, published September 15, 2016). [0043] In preferred embodiments, the additive manufacturing apparatus is a bottom-up stereolithography apparatus (including but not limited to apparatus carrying out CLIP), employing a window cassette, such as described in B. Feller et al., Three-dimensional printing with build plates having reduced pressure and/or channels for increased fluid flow, PCT Patent Application Pub. No. WO 2018/006029, or B. Feller et al., Three-dimensional printing method and apparatus for reducing bubbles by de-gassing through build plate, PCT Patent Application Pub. No. WO 2018/006018 (where the“build plate” therein refers to the “window cassette” as described herein).

[0044] FIGS. 1-2 illustrate first non-limiting examples of embodiments of the present invention. The stereolithography apparatus, includes a window cassette (discussed further below) removably connected to the apparatus top deck (21); a carrier platform (23) positioned above the window and configured for defining a build region between the semipermeable top portion of the window and the carrier platform (23); a drive (24) operatively associated with the carrier platform and the window and configured for advancing the window and the carrier platform away from one another; a light source (22) (e.g., a UV light and associated micromirror array) positioned beneath the window; at least one temperature sensor (28) operatively associated with the build region and configured to sense (directly or indirectly) the temperature of a polymerizable resin in the build region; and a controller (27), including a temperature controller, operatively associated with the temperature sensor and the at least one thermoelectric device, the controller configured to activate the at least one thermoelectric device to maintain the temperature of a polymerizable resin in the build region above a predetermined minimum temperature (e.g, at least 30 or 35 °C) and/or below a predetermined maximum temperature (e.g, not more than 40, 50, 60, 80, or 100 °C). Other aspects of the controller (27), for operating the drive (24) and light source (22), can be carried out in accordance with known techniques for bottom-up stereolithography, or variations thereof that will be apparent to those skilled in the art.

[0045] The removable window cassette includes a a light-transmissive window having a rigid bottom portion (31) and a semipermeable top portion (32), with the rigid bottom portion comprised of a thermally conductive material; a circumferential frame (33) surrounding the window and into which the window is recessed, the frame having a top portion, a bottom portion, and an internal wall portion, the frame internal wall portion defining with the window semipermeable top portion a well into which a polymerizable liquid may be received; and at least one thermoelectric device (34) in the circumferential frame and in thermal contact with the rigid bottom portion. The frame is optionally, but preferably, rectangular, and the window is preferably generally flat and planar. The bottom portion (31) may be comprised of any suitable light-transmissive, thermally conductive, material, such as of glass, sapphire, transparent aluminum (ALON). The semipermeable top portion is preferably comprised of a fluoropolymer. The window top portion (32) and the window bottom portion (31) have opposing internal surfaces that are preferably directly or indirectly adhered to one another, and preferably in thermal contact with one another (e.g., through the entire surface area of the faces, except as interrupted by the channels of a fluid channel bed as discussed further below).

[0046] In some embodiments, the window cassette includes a fluid channel bed formed in the window between the bottom portion and the top portion. Such a channel bed will typically have a first header, a second header, and a channel array therebetween, with said channel array configured to supply an inhibitor of polymerization through the semipermeable top portion. A first fluid inlet can be included in the said circumferential frame bottom portion and connected to the first channel bed header; and a second fluid inlet can be included in the circumferential frame bottom portion and connected to the second channel bed header. For a window cassette that includes a fluid channel bed, the stereolithography apparatus can further comprise a fluid (e.g., an oxygen-enriched gas) supply system operatively associated with the first fluid inlet and the second fluid inlet (e.g., a fluid source operatively associated with the first inlet, and a vacuum source operatively associated with the second inlet, optionally switchable therebetween). Additional details are given in B. Feller et al., Three-dimensional printing with build plates having reduced pressure and/or channels for increased fluid flow, PCT Patent Application Pub. No. WO 2018/006029, and B. Feller et al., Three-dimensional printing method and apparatus for reducing bubbles by de-gassing through build plate, PCT Patent Application Pub. No. WO 2018/006018.

[0047] The at least one thermoelectric device (34) preferably comprises a plurality (e.g., 2, 3, 4 or more) thermoelectric devices, which may be of the same type, or different from one another. Any suitable thermoelectric device can be used to carry out the present invention, including resistive heaters (e.g., metal, polymer, and composite resistive heaters), ultrasonic or piezoelectric heaters, thermoelectric devices relying on the thermoelectric or Peltier effect (e.g., “Peltier devices” for heating and/or cooling), etc., including combinations thereof. Examples include but are not limited to those set forth in US Patents No. 6,300,150 and U.S. Patent Publication Nos. 2007/0028956 and 2006/0086118. Heat sinks, particularly when cooling is carried out, may optionally be thermally coupled to the thermoelectric device ( e.g ., by direct contact or through a thermally conductive coupling), as discussed further below. In some embodiments, Peltier devices are preferred, as they can be used to both heat and cool resin by reversing polarity (though Peltier coolers can be used in combination with dedicated heaters, such as resistive heaters, as well).

[0048] In some embodiments, the controller is configured to both heat the resin with the thermoelectric device(s), when the temperature of the resin is below a predetermined minimum (e.g., at the beginning, or early stages, of production of a particular object or group of objects), and, cool the resin when the temperature of the resin approaches a predetermined maximum). Such cooling as temperature of the resin increases during production (due to the exothermic nature of the polymerization) may be advantageous where the other option to avoiding excessively high temperatures is to slow down the speed of production.

[0049] The predetermined minimum temperature may, for example, be at least 30 or 35 °C. In some embodiments, the method may further comprise the step of warming the resin to an actual temperature greater than the predetermined minimum temperature prior to the initial production steps. And in some embodiments, the activating can be discontinued (or in the case of a Peltier device, function changed and cooling initiated initiated) prior to the resin actual temperature exceeding a predetermined maximum temperature (e.g., not more than 40, 50, 60, 80, or 100 °C).

[0050] As noted above, one or more temperature sensors (28) are operatively associated with the build region, and are configured to sense, directly or indirectly, the temperature of a polymerizable resin in the build region. Any suitable temperature sensor(s) can be used, including contact or non-contact temperature sensors such as infrared sensors, pyrometers, microbolometers, thermal cameras, thermistors, etc.). For example, an IR sensor can be positioned beneath the window, and directed to the bottom of the window. Such an IR sensor (or sensors, if a plurality are employed) can be tuned to a wavelength such that it primarily senses the temperature of the window itself as a surrogate for the temperature of the resin (with the controller 27 adjusted or configured accordingly), or can be a sensor which is tuned to a wavelength that looks through the window and more directly sense the temperature of the resin.

[0051] Controller 27 may comprise at least one temperature controller is operatively associated with the temperature sensor and the infrared heat source, the controller configured to intermittently activate the heat source. Suitable controllers include proportional-integral- derivative (PID) controllers, proportional integral (PI) controllers, dynamic matrix controllers (DMCs), etc. (See, e.g., US Patent Nos. 9,841,186 9,795,528; 9,766,287; 9,220,362). The controllers may perform pulse-width modulation to each the infrared heat source. The controllers may be configured to maintain the resin within a predetermined temperature range of from 30 or 35 °C to 60, 80, or 100 °C, or more. In addition, where a plurality of heat sources are used, each focused on separate (optionally partially overlapping) regions of the window, the heat sources may be independently controlled by the temperature controller(s), such as where different regions of the window are subject to different heat input (e.g., from heat of polymerization) or heat drain (e.g., from contact with an adjacent supporting structure, contact to a carrier plate, etcl). For such separate control of the heat sources, multiple, separately focused or directed, temperature sensor may be used, or one or more infrared camera (providing a thermal map) can be used to provide independent data for independent control of the the multiple heat sources.

[0052] The heater (34) and/or coolers (35) are preferably electrically connected to the controller (37) by a connector, such as a latching connector or a break-away electrical connector. Such break-away connectors typically comprised two mating members, one of which is connected to the frame (33), and the other of which is connected to a flexible line which is in turn connected to controller (27). Such connectors are known and described in, for example, US Patent Nos. 2,933,711; 3,363,214; 7,517,222; and 7,874,844, the disclosures of which are incorporated herein by reference in their entirety.

[0053] FIGS. 3-4 illustrate second non-limiting examples of the present invention, where the thermoelectric devices 36 comprise Peltier devices configured to operate in a cooling mode. Here, heat sinks 36 are connected to the frame 33, and are in thermal contact to the Peltier devices 35, to dissipate heat when the Peltier device is cooling the resin. Conversely, if the Peltier devices are operated in a mode of heating the resin, the heat sinks will be cooled (or, will withdraw heat from the ambient atmosphere). Additional components of a cassette or apparatus of FIGS. 3-4 may be as described above.

[0054] FIGS. 5-6 illustrate third non-limiting examples of the present invention. In this embodiment, the heat sinks 36’ are connected to the apparatus upper deck 21, and access ports, slots, or openings are provided in the window cassette frame 33 so that the Peltier devices can contact the heat sinks 36’ when the window cassette is mounted on the stereolithography apparatus upper deck 21. Additional components of a cassette or apparatus of FIGS. 5-6 may be as described above. [0055] FIG. 7 illustrates a fourth non-limiting embodiment of the present invention. In this embodiment no separate heat sink is provided for the Peltier device 35, as the frame 33’ and/or the upper deck 21’ of the apparatus are formed from a thermally conductive material and configured in contact with the Peltier device so that they serve as the heat sink. Additional components of a cassette or apparatus of FIG. 7 may be as described above.

[0056] The foregoing is illustrative of the present invention, and is not to be construed as limiting thereof. The invention is defined by the following claims, with equivalents of the claims to be included therein.

Claims

We claim:

1. A removable window cassette for a bottom-up stereolithography apparatus, comprising:

(a) a light-transmissive window having a rigid bottom portion and a semipermeable top portion, with said rigid bottom portion comprised of a thermally conductive material;

(b) a circumferential frame surrounding said window and into which said window is recessed, said frame having a top portion, a bottom portion, and an internal wall portion, said frame internal wall portion defining with said window semipermeable top portion a well into which a polymerizable liquid may be received; and

(c) at least one thermoelectric device in said circumferential frame and in thermal contact with said rigid bottom portion.

2. The cassette of claim 1, wherein said at least one thermoelectric device comprises a plurality of thermoelectric devices.

3. The cassette of any preceding claim, wherein said at least one thermoelectric device comprises (i) at least one resistive heater, (ii) at least one Peltier device, or (Hi) both at least one resistive heater and at least one Peltier device.

4. The cassette of any preceding claim, wherein said rigid bottom portion is comprised of glass, sapphire, or transparent aluminum (ALON).

6. The cassette of any preceding claim, wherein said window semipermeable top portion is comprised of a fluoropolymer.

7. The cassette of any preceding claim, further comprising:

a fluid channel bed formed in said window between said bottom portion and said top portion, said channel bed having a first header, a second header, and a channel array therebetween, with said channel array configured to supply an inhibitor of polymerization through said semipermeable top portion;

a first fluid inlet in said circumferential frame bottom portion, said first fluid inlet connected to said first channel bed header; and a second fluid inlet in said circumferential frame bottom portion, said second fluid inlet connected to said second channel bed header.

8. The cassette of any preceding claim, wherein said window top portion and said window bottom portion have opposing internal surfaces directly or indirectly adhered to one another, and in thermal contact with one another (e.g., through the entire surface area of the faces, except as interrupted by the channels of said fluid channel bed).

9. The cassette of any preceding claim, wherein said circumferential frame is rectangular.

10. The cassette of any preceding claim, wherein said window is generally flat and planar.

11. A stereolithography apparatus, comprising:

a removable window cassette of any preceding claim;

a carrier platform positioned above said window and configured for defining a build region between said semipermeable top portion and said carrier platform;

a drive operatively associated with said carrier platform and said window and configured for advancing said window and said carrier platform away from one another; a light source positioned beneath said window;

at least one temperature sensor operatively associated with said build region and configured to sense (directly or indirectly) the temperature of a polymerizable resin in said build region; and

a temperature controller operatively associated with said temperature sensor and said at least one thermoelectric device, said controller configured to activate said at least one thermoelectric device to maintain the temperature of a polymerizable resin in said build region above a predetermined minimum temperature ( e.g ., at least 30 or 35 °C) and/or below a predetermined maximum temperature (e.g., not more than 40, 50, 60, 80, or 100 °C).

12. The apparatus of claim 11, wherein said controller comprises a proportional- integral-derivative (PID) controller, a proportional integral (PI) controller, or a dynamic matrix controller (DMC).

13. The apparatus of any preceding claim, wherein said at least one thermoelectric device and said controller are configured for both heating and cooling said resin.

14. The apparatus of any preceding claim, wherein said temperature sensor comprises a contact or non-contact temperature sensor operatively associated with said window.

15. The apparatus of any preceding claim, further comprising a fluid (e.g., an oxygen-enriched gas) supply system operatively associated with said first fluid inlet and said second fluid inlet (e.g., a fluid source operatively associated with said first inlet, and a vacuum source operatively associated with said second inlet).

16. The apparatus of any preceding claim, further comprising a break-away electrical connector (e.g., a magnetic break-away connector) on said frame and electrically interconnecting said at least one thermoelectric device to said temperature controller.