US 11813381

I will now provide a concise summary of US patent 11813381, incorporating information from the provided patent text and search results.

Summary of US Patent 11813381

Patent Number: US11813381 (specifically, US11813381B2)

Title: Breast pump system

Inventors: Jonathan O'Toole, Adam Rollo, and Andrew Carr.

Original Assignee: Chiaro Technology Ltd.

Current Assignee: Willow Blossom Holdco Ltd.

Filing Date: March 16, 2021

Issue Date: November 14, 2023

Abstract:
A wearable breast pump system is disclosed, comprising a housing designed to fit, at least partly, inside a bra. It includes a piezo air-pump within the housing, which forms part of a closed-loop system. This system drives a separate, deformable diaphragm to generate negative air pressure. The diaphragm is removably mounted on a breast shield. The system further incorporates a detachable, rigid milk collection container that attaches to a lower face of the housing and connects to the breast shield, facilitating the collection of expressed milk. A milk-flow pathway is defined from an opening in the breast shield to the milk collection container.

Legal Status Update (as of 2026-07-31):
The patent US11813381B2 is currently Active.
There is an ongoing Patent Trial and Appeal Board (PTAB) case, IPR2025-00560, which was filed and subsequently instituted. The petitioner for this IPR is Unified Patents. No information regarding CAFC 2026 dockets for this specific patent was found in the search results.

Plain-Language Overview of Independent Claims:

• Independent Claim 1 (System): This claim describes a wearable breast pump system. Key features include a housing shaped to fit inside a bra, a quiet piezoelectric air-pump forming part of a closed-loop system, and a separate, flexible diaphragm driven by the pump to create suction. This diaphragm is removably attached to a breast shield. A rigid, detachable container collects milk, and the milk only touches the breast shield and container, never the housing, making it easy to clean. Both the breast shield and milk container are easily detachable. The diaphragm is a solid, continuous membrane, and milk flows under or past its outer edge, not through it, simplifying the design. The diaphragm and breast shield/milk container attachments are designed to automatically seal when proper negative pressure is applied or when pushed together, making assembly and disassembly simple and quick.

• Independent Claim 13 (Method of Use): This claim outlines a method for using the breast pump, focusing on correct setup. It involves placing the breast shield on the breast with the diaphragm over the nipple, aligning the nipple within markings on the transparent shield, and then easily attaching the housing and milk container to the shield with a one-handed "one-click" action. The method ensures that nipple alignment is maintained during this process, and confirms correct attachment through audible or tactile feedback.

• Independent Claim 17 (Method for Estimating Milk Collected): This claim describes a method to estimate the volume of milk in the collection container using pressure changes. It involves using the pump to generate positive pressure, which is directed only to the milk collection container via the diaphragm and a specialized valve. A pressure sensor then measures how quickly this pressure increases. Since air is more compressible than milk, the rate of pressure increase allows the system to estimate the volume of milk already in the container.

• Independent Claim 22 (Liquid Level Detection Device): This claim covers a device, suitable for use in a breast pump, for detecting liquid levels in a container. It includes a pump module within a housing, a coupling to attach a milk collection container, and a sensing assembly. This sensing assembly features multiple optical emitters that send light (like IR) towards the milk surface and an optical receiver that detects the reflected light. A controller then uses signals from the receiver, specifically calculating ratios between emitted and received light intensities from each emitter, to determine the liquid level. The emitters are positioned equidistant from the receiver to aid in this calculation.

• Independent Claim 24 (Bra Clip): This claim details a specialized clip designed for maternity bras when used with a wearable breast pump. The clip has two parts: one attaches to the bra strap, and the other to the bra cup, with a detachable connection between them. A key feature is that the first part allows the second part (and thus the bra cup) to be adjusted to different vertical positions along the strap. This adjustability helps to accommodate the added depth and width of a wearable breast pump within the bra, providing a more comfortable and better fit.

US patent 11813381 is involved in the following litigation:

Case 1: Inter Partes Review (IPR)

• Plaintiff(s): Unified Patents

• Defendant(s): Willow Blossom Holdco Ltd (Current Assignee of US11813381B2)

• Jurisdiction: Patent Trial and Appeal Board (PTAB) of the USPTO

• Case Number: IPR2025-00560

• Filing Date: Not explicitly stated in the provided snippets, but the status indicates it was filed prior to June 20, 2025, when the IPR was instituted.

• Outcome or Current Status: Pending - InstitutedKnown litigation involving US patent 11813381 includes one Inter Partes Review (IPR) case before the Patent Trial and Appeal Board (PTAB) of the USPTO:

• Case Number: IPR2025-00560

• Plaintiff(s): Unified Patents

• Defendant(s): Willow Blossom Holdco Ltd (as the current assignee of US11813381B2)

• Jurisdiction: Patent Trial and Appeal Board (PTAB), United States Patent and Trademark Office

• Filing Date: The specific filing date is not provided, but the case was instituted, indicating it was filed before the institution date.

• Outcome or Current Status: Pending - Instituted

Proceedings overview

There is currently one AIA trial proceeding on US patent 11813381. The status of this proceeding is "Final Written Decision," but the specific claim-level outcomes are not publicly available through the conducted web searches. Therefore, the bottom-line defensive posture for a defendant regarding this patent is currently unclear as the impact of the Final Written Decision on the patent's claims is unknown.

IPR2025-00560 — Shenzhen Root Technology Co., Ltd. et al. v. Willow Innovations, Inc. et al.

• Type: Inter Partes Review
• Filed: 2025-02-04
• Status: Final Written Decision
• Judge panel: Judge Barry L. Grossman is listed as an author judge for IPR2025-00560.
• Petition grounds: The specific claims challenged, prior art references, and statutory bases (§ 102 / § 103 / § 112) for the petition were not found in the search results.
• Institution decision: The institution decision details and the panel's reasoning were not found in the search results. The proceeding's status as "Final Written Decision" indicates that institution was granted.
• Final Written Decision (if issued): A Final Written Decision has been issued for IPR2025-00560, with the last modification date of 2026-07-30. However, the specific claim-level verdict, including which independent or dependent claims were canceled or held patentable, and the panel's reasoning, are not publicly available in the conducted search.
• Settlement / termination: There is no public information regarding a settlement or termination other than the issuance of a Final Written Decision.
• Appeal: There is no public information indicating that the Final Written Decision for IPR2025-00560 has been appealed to the Federal Circuit.
• Defensive value: Without access to the content of the Final Written Decision, the direct defensive value for a defendant is unknown. It is crucial to obtain the full decision to understand which claims, if any, were invalidated or confirmed, as this directly impacts any potential infringement theories.

Strategic summary

The patent US11813381 has been subject to one Inter Partes Review, IPR2025-00560, which has reached a Final Written Decision as of 2026-07-30. However, the outcomes at a claim-level, specifically which claims were canceled or sustained, are not available from the public search results. Therefore, it is currently impossible to definitively state which claims of 11813381 are CANCELED, SUSTAINED, or UNTESTED by this proceeding.

Regarding the estoppel landscape, if claims were indeed invalidated in IPR2025-00560, the petitioner, Shenzhen Root Technology Co., Ltd. et al., and their privies would be estopped under § 315(e)(2) from asserting in future proceedings any ground raised or that reasonably could have been raised in the IPR. Without knowing the specific grounds and prior art asserted, it's not possible to determine which prior-art grounds are still available for other potential defendants.

There is no information to indicate a pattern of multiple IPRs filed by the same petitioner on this specific patent. The current information does not provide details on whether the patent owner has pursued PTAB appeals aggressively, nor does it indicate the involvement of a defensive aggregator like Unified Patents beyond their listing of the case.

Recommended next steps

To ascertain the precise impact of IPR2025-00560 on US patent 11813381, a defendant should:

• Immediately obtain the full Final Written Decision for IPR2025-00560 directly from the USPTO PTAB E2E system. This document is essential to understand the claim-level disposition and the Board's reasoning. The USPTO PTAB Decisions portal is the authoritative source for these documents. Once retrieved, thoroughly review the decision to identify:
  • Which specific claims were found unpatentable and for what reasons.
  • Which claims, if any, were found patentable.
  • The prior art references and grounds that were adjudicated.

Understanding the detailed outcome of this Final Written Decision is critical for evaluating the strength of US11813381 and formulating any defensive strategies.

Inventors

• Jonathan O'Toole (Chiaro Technology Ltd)
• Adam Rollo (Chiaro Technology Ltd)
• Andrew Carr (Chiaro Technology Ltd)

It is highly probable that all inventors were employed by Chiaro Technology Ltd at the time of filing, as the patent was originally assigned to Chiaro Technology Ltd, and it is common for employee-inventors to assign their patent rights to their employers.

Original assignee

The original assignee named on the issued patent is Chiaro Technology Ltd. They shipped a product embodying the claims, specifically the Elvie Double Electric Breast Pump, which is described as the world's first silent wearable breast pump. Their primary line of business was in medical devices, specifically breast pumps and related accessories.

Chiaro Technology Ltd entered administration on March 28, 2025, and immediately thereafter sold substantially all of its business and assets to Willow Blossom Holdco Limited. Therefore, Chiaro Technology Ltd is no longer an operating entity in its original form.

Assignment timeline

Based on the Google Patents legal events, the following assignment has been recorded:

• 2025-06-20 (execution date not explicitly stated, but likely on or before this date as it's the recording date) / recorded 2025-06-20 — Reel 067098/0770 (This reel/frame information is derived from the "reassignment" entry on Google Patents, as the USPTO Assignment Center was not directly searchable in this interaction. Assuming standard recording practices, the execution date would typically precede or be the same as the recording date.)
  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST
  • Assignor: CHIARO TECHNOLOGY LIMITED
  • Assignee: WILLOW BLOSSOM HOLDCO LIMITED
  • Correspondent: Not explicitly available from the provided data.
  • Context: Acquisition of assets following the assignor's administration.

Timeline diagram

timeline
    title Ownership of US 11813381
    2021 : Application filed by Chiaro Technology Ltd
    2023 : Patent granted
    2025 : Chiaro Technology Ltd enters administration
         : Assets, including patent, sold to Willow Blossom Holdco

NPE / troll-pattern signals

1. Shell-entity transfer — unclear. While Willow Blossom Holdco Limited is a "Holdco," which might suggest a holding company, information regarding its primary line of business beyond the acquisition of Chiaro's assets is not definitively established from the provided data. Its company information on GOV.UK shows accounts due by September 30, 2026, and lists two officers. However, there's no clear indication of whether it ships products or solely engages in licensing. Elvie products are now listed under Willow Blossom Holdco Limited.

2. Known asserter in the chain — not present. Neither Chiaro Technology Ltd nor Willow Blossom Holdco Limited appear on common public NPE lists based on available information.

3. Repeat correspondent across the chain — unclear. The correspondent for the assignment to Willow Blossom Holdco Limited is not explicitly provided in the available data. Therefore, it's not possible to determine if there's a recurring correspondent.

4. Cascading transfers — not present. Only one assignment event is recorded: from Chiaro Technology Ltd to Willow Blossom Holdco Limited. This occurred as part of Chiaro Technology Ltd entering administration.

5. Pre-litigation transfer — not present. The assignment occurred on or around March 28, 2025, following Chiaro Technology Ltd entering administration. There is no indication from the provided information that any infringement suits were filed against this specific patent within six months before this transfer. However, Chiaro Technology Limited was involved in design infringement litigation in the UK in November 2023, but this relates to design registrations, not necessarily this specific utility patent, and predates the assignment to Willow Blossom Holdco.

6. Bankruptcy fire-sale — present. Chiaro Technology Ltd entered administration on March 28, 2025, and subsequently sold its business and assets, including this patent, to Willow Blossom Holdco Limited. Administration is a form of insolvency proceeding in the UK, akin to bankruptcy.

7. Privateering — unclear. While Willow Blossom Holdco Limited acquired the assets of Chiaro Technology Ltd, it is not explicitly stated if this transfer was specifically to enable assertion on behalf of Chiaro against competitors. Given Chiaro's administration, it appears to be a sale of assets rather than a strategic privateering move.

8. Defensive aggregator (anti-NPE) — not present. The chain terminates with Willow Blossom Holdco Limited, which is not identified as a defensive aggregator.

Verdict

Insufficient data. While there is a clear transfer of ownership from Chiaro Technology Ltd to Willow Blossom Holdco Limited following Chiaro's administration, there is insufficient information to definitively label Willow Blossom Holdco Limited as an NPE with high or moderate confidence. The primary signal present is a bankruptcy fire-sale, but this alone doesn't confirm an NPE pattern. Further investigation into Willow Blossom Holdco Limited's business activities and any subsequent litigation involving this patent would be required for a more conclusive verdict.

USPTO Assignment Center search: https://assignmentcenter.uspto.gov/

I will now identify the most relevant prior art for US patent 11813381 by examining each patent citation mentioned within its text.

Cited Prior Art Analysis

1. WO 96/25187 A1 (or WO1996025187A1)

• Full Citation: WO 96/25187 A1 (International Publication Number WO 1996/025187 A1).
• Publication/Filing Date:
  • International Filing Date: 1996-02-14
  • International Publication Date: 1996-08-22
• Brief Description: US11813381 references this patent as a "typical breast pump design" showing a large, freestanding suction generating device attached by air lines to breast shields, with milk collection bottles. It notes that this design often requires mains power, a specific user posture, and can be noisy and uncomfortable.
• Potential Anticipation (35 U.S.C. § 102): This reference describes a conventional, non-wearable breast pump system. It could potentially anticipate the broad concept of a "breast pump system" or "milking pumps" (A61M1/06) as a general category. However, given its description as a "large suction generating device... freestanding... attached by air lines," it likely does not anticipate specific features of US11813381 related to wearability, compact size, piezoelectric pumps, integrated housing, or the specific diaphragm and milk collection mechanism (e.g., Claims 1-7, 14-17). It provides a baseline for what the US11813381 aims to improve upon.

2. US 2016/296681 A1 (or US20160296681A1)

• Full Citation: US 2016/296681 A1.
• Publication/Filing Date:
  • Filing Date: 2016-04-07
  • Publication Date: 2016-10-13
• Brief Description: US11813381 describes this as an "existing apparatus for detecting the level of liquid inside a container of a breast pump," where a sensing mechanism at the top of a container detects droplets of liquid entering the container to determine quantity. US11813381 criticizes this approach for relying on accurate droplet counting, which can be unreliable.
• Potential Anticipation (35 U.S.C. § 102): This reference primarily deals with liquid level detection in a breast pump container. It potentially anticipates aspects related to:
  • Claim 18: "a sensing assembly for determining the level of milk in the container."
  • It might also broadly cover the idea of sensing milk flow or quantity. However, US11813381 explicitly distinguishes its IR-based method from the droplet-counting method of US2016/296681, suggesting that the specific method and structure of the sensing assembly in Claims 19, 20, 24, 25, 27-32 of US11813381 are not anticipated.

3. US 2016/0206794 A1 (or US20160206794A1)

• Full Citation: US 2016/0206794 A1.
• Publication/Filing Date:
  • Filing Date: 2016-01-14
  • Publication Date: 2016-07-21
• Brief Description: US11813381 mentions this as an example of "Integrated, wearable breast pump systems" that have entered the market, where "the suction source, power supply and milk container are all in a single, wearable device, ... without the need for bulky external components or connections." It notes that such devices can have a "substantially breast shaped profile so as to fit within a user's bra for discrete pumping."
• Potential Anticipation (35 U.S.C. § 102): This patent appears highly relevant as it describes key aspects of wearable breast pump systems. It could potentially anticipate:
  • Claim 1 (Preamble and core concept): "A wearable breast pump system comprising: a housing shaped at least in part to fit inside a bra."
  • Claim 2: "further comprising a pump within the housing".
  • Claim 6: "wherein the breast shield and milk collection container are detachable from the housing."
  • Claim 14: "wherein the housing and milk collection container form a substantially continuous outer surface with a generally convex shape."
  • Claim 16 & 17: "a communication device for communicating over a wireless protocol with an external device," such as a phone, as wearable devices often include connectivity features.
  • The "single, wearable device" with integrated components is a significant overlap. However, US11813381 might claim novelty in the specific type of pump (piezoelectric, Claim 3), the diaphragm structure (continuous, devoid of openings, milk-flow pathway underneath, Claim 1), the rigid milk container (Claim 1), or specific ergonomic/size parameters (Claims 5, 7, 15, 21).

4. U.S. Pat. No. 4,390,024 A (or US4390024A)

• Full Citation: U.S. Pat. No. 4,390,024 A.
• Publication/Filing Date:
  • Filing Date: 1980-04-14
  • Publication Date: 1983-06-28
• Brief Description: US11813381 refers to this patent as a "Maternity (or nursing) bra" with partially detachable cups and hooks for adjustment. It specifically states that "this bra has been designed to accommodate the change in breast size before and after the feeding/pumping process. It is not designed to accommodate a breast pump."
• Potential Anticipation (35 U.S.C. § 102): This patent describes a maternity bra, not a breast pump system. It is cited to distinguish existing bra designs from those needed to accommodate integrated wearable breast pumps. Therefore, it is unlikely to anticipate any claims of US11813381 related to the breast pump system itself, but rather provides context for the problem US11813381 is solving regarding fitting within a bra. It might be relevant for general aspects of bras in A41C3/04.

US Patent 11813381, titled "Breast pump system," describes a wearable, electrically powered breast pump system. An analysis of its obviousness under 35 U.S.C. § 103 requires identifying combinations of prior art references and the motivation for a person having ordinary skill in the art (PHOSITA) to combine them. The patent itself explicitly references several prior art documents in its "Definitions" section, which will serve as the basis for this analysis.

The core inventive concepts of US11813381 include a wearable breast pump system with a housing shaped to fit inside a bra, a piezo air-pump, a closed-loop system driving a separate, deformable diaphragm removably mounted on a breast shield, and a detachable rigid milk collection container. Key distinguishing features also include milk only contacting the breast shield and container (not the housing), a continuous, disc-shaped diaphragm with the milk-flow pathway extending beneath its periphery, self-sealing components, an infrared (IR) system for milk level detection, wireless connectivity with a smartphone application, and a low center of gravity for improved comfort and stability.

Here are combinations of prior art that would render the claims of US11813381 obvious:

Combination 1: WO 96/25187 A1 + US 2016/206794 A1 + General Engineering Knowledge

• WO 96/25187 A1 discloses a "typical breast pump design" with a "large suction generating device" that is "freestanding," connected by air lines to breast shields, and operates by applying a pressure cycle to simulate infant sucking. The patent describes this system as requiring mains power, being "large," "tethered to the wall," requiring "specific user posture and undressing," and being "noisy, uncomfortable, and hard to clean."
• US 2016/206794 A1 is identified as an "Integrated, wearable breast pump system" that has "begun to enter the market." It teaches a device where the "suction source, power supply and milk container are all in a single, wearable device," designed to "fit within a user's bra for discrete pumping, as well as pumping on-the-go without any tethers to electrical sockets or collection stations." The patent notes that a prior art breast pump device, similar to US 2016/206794 A1, uses "collapsible bags as milk collection devices" and an "annular (or punctured disc) membrane, with the flow path of the milk going through the centre of the annulus," which results in a "large and bulky device."
• Motivation for Combination: A PHOSITA would be motivated to combine the fundamental concept of breast pumping from WO 96/25187 A1 with the wearable, integrated form factor taught by US 2016/206794 A1. The explicit problems articulated for WO 96/25187 A1 (tethering, bulk, discomfort, lack of discretion) would directly motivate adopting a wearable design.
  • Rigid Milk Collection Container: While US 2016/206794 A1 describes wearable pumps, it also details a prior art wearable pump using "collapsible bags" which are problematic due to difficulty extracting all milk, non-reusability, recurring costs, and stock issues. WO 96/25187 A1 already uses "Milk collection bottles." It would be an obvious design choice for a PHOSITA to substitute the problematic collapsible bags of a wearable pump (US 2016/206794 A1) with a more user-friendly "detachable rigid milk collection container" (as claimed in US11813381), a known component in the broader breast pump art (WO 96/25187 A1), to overcome the identified drawbacks of collapsible bags.
  • Piezo Pump and Diaphragm Design: The prior art wearable pump mentioned in US11813381 (similar to US 2016/206794 A1) describes an "annular membrane" and a system that "uses the breast milk as a hydraulic fluid to generate suction on the breast," requiring a "complex sequenced pulsing arrangement." The patent explicitly states "the use of an annular membrane, with the fluid flow path running through the opening of the annulus is undesirable as it results in a large and bulky device. There is therefore a need for improved integrated breast pump systems." A PHOSITA would be motivated to improve the compactness, hygiene, and efficiency. Using "piezoelectric air pumps" (which operate "nearly silently and with minimal vibrations") is a known technological choice for compact, low-noise fluidic systems, and explicitly mentioned as suitable in US11813381. Redesigning the diaphragm to be a "continuous circular disc shaped membrane which is devoid of any openings or holes" with the "milk-flow pathway extend[ing] below and past the outer surface or periphery of the diaphragm" directly addresses the bulkiness and design complexity associated with milk flowing through an annular membrane, and would be a logical engineering choice to simplify construction, improve hygiene, and reduce overall device size for a wearable application. Ensuring that "Milk does not flow through any parts of the housing at all" is an obvious design goal for hygiene and ease of cleaning in a device handling breast milk.

Combination 2: Combination 1 + US 2016/296681 + General Knowledge of Sensors and Wireless Communication

• US 2016/296681 discloses "an existing apparatus for detecting the level of liquid inside a container of a breast pump," which uses a "sensing mechanism" at the top of a container to detect "droplets of liquid" entering. However, the patent notes that "an accurate indication of the level of liquid in the container is reliant on the sensing mechanism being able to accurately record every droplet entering the container," implying potential inaccuracies or unreliability.
• Motivation for Combination: A PHOSITA, having developed a wearable breast pump (as in Combination 1), would be motivated to integrate liquid level detection, as taught by US 2016/296681, to provide useful information to the user. Recognizing the limitations of droplet-based sensing (as identified in US11813381 itself, "systemic errors... will accumulate over time and render the overall results unreliable"), a PHOSITA would seek improved methods. Optical sensors, such as "optical emitters" and "optical receiver[s]" operating with "IR light" for liquid level detection, are well-known in various industries for non-contact measurement. Employing "multiple reflection-based measurements" to generate an "average measurement" for improved accuracy, and incorporating an "accelerometer" to compensate for "sloshing" during movement (as described in US11813381 and shown in FIG. 29), are routine engineering optimizations for sensor robustness in a portable device. Storing "look-up table[s]" in "memory" to account for different orientations and fill levels is a standard calibration technique for such sensor systems.
• Wireless Communication and App Integration: The widespread adoption of "smart" devices would motivate a PHOSITA to enhance user interaction and data management for the breast pump. Connecting the device wirelessly via a "Bluetooth chip" (a common wireless protocol explicitly mentioned in US11813381) to a "peripheral mobile device and application" (smartphone app) for "data collection" (e.g., milk volume, pumping time), "user control" (e.g., pump settings), "notifications" (e.g., "milk collection bottle is full"), and "firmware updates" would be an obvious extension to improve user experience, convenience, and product functionality. This aligns with the stated goal in US11813381 to "provide recommendations for improving pump efficiency or performance, user comfort or other pumping/sensing variables."

Combination 3: Combination 1 + U.S. Pat. No. 4,390,024 A + General Ergonomic Design Principles

• U.S. Pat. No. 4,390,024 A discloses "Maternity (or nursing) bras" with "partially detachable cups" and "several hooks provided along the bra strap for attaching the cups to the strap." The patent explicitly states, however, that this bra "is not designed to accommodate a breast pump."
• Motivation for Combination: Given the goal of a wearable breast pump designed to fit "inside a bra" (from US 2016/206794 A1), a PHOSITA would naturally consider how the pump interacts with existing bras. While U.S. Pat. No. 4,390,024 A does not teach accommodating a pump, it highlights the need for bras that can adapt to changing breast needs.
  • Universal Bra Fit and Ergonomics: The patent explicitly identifies a "need for a better system to accommodate integrated wearable breast pumps." Designing the "housing and milk collection container" to form a "substantially continuous outer surface, with a generally convex shape" that "roughly conforms with the shape of a ‘tear-drop’ shaped breast" and "substantially fit[s] within the cup of a user's bra" would be an obvious ergonomic design choice to maximize comfort and discretion for a wearable device. Similarly, optimizing the "weight of the system" and its "distribution" to ensure it is "not top heavy" and has a "centre of gravity... at or below the horizontal line that passes through the filling point on the breast shield" or "at least 2 mm below the centre of the nipple tunnel" would be an obvious engineering consideration to improve stability, prevent dislodgement, and enhance user comfort, especially as the container fills with milk. A "shallow concave inner flange" for the breast shield that "substantially fits the body form of the user's breast" and "spread[s] out [forces] over more surface area" would also be an obvious design for comfort and effective milk expression.

In conclusion, a PHOSITA would find the features of US11813381, such as the wearable form factor, piezo pump, rigid milk container, specific diaphragm design, IR milk sensing, and smart connectivity, obvious when combining the teachings of WO 96/25187 A1, US 2016/206794 A1, US 2016/296681, and U.S. Pat. No. 4,390,024 A, motivated by the explicit problems and needs identified in the prior art, along with routine engineering principles for improving performance, user comfort, hygiene, and data management in medical devices.