🤖 AI Engineer

Hi, I'm Joy Chen

I'm an AI Engineer who builds full-stack, AI-powered products end to end, from tool-calling agents and RAG pipelines to shipped, deployed apps. My background training deep learning models on medical imaging data gives me a research-grade rigour about evaluation and edge cases that a lot of AI engineering work skips.

MSc
Medical Imaging Science
Univ. of Manchester, Merit
BEng
Biomedical Engineering
Shantou University, Top 30%
Who I Am

Building AI end to end
from model to product

I hold a BEng in Biomedical Engineering from Shantou University and an MSc in Medical Imaging Science from the University of Manchester, where I graduated with Merit, a background that gave me a solid foundation in deep learning before I moved into building full-stack AI products. I'm a graduate visa holder, so no sponsorship is needed.

What I enjoy most is taking a problem and working through it systematically end to end: designing a RAG pipeline, wiring up an LLM provider, shipping a working app, or further back, writing a segmentation pipeline and reviewing hundreds of landmark annotations. Same mindset, different stack.

The domain background behind that: CT and MRI processing, image segmentation, statistical shape modelling and 3D reconstruction, plus the research habits that come with a lab, experimental design and writing up what you find.

AI / LLM Engineering
Tool-Calling AgentsAgent EvaluationVercel AI SDKRAGLLM IntegrationStructured OutputEmbeddingsPrompt Engineering
Full-Stack Development
Next.jsReactTypeScriptTailwind CSSDrizzle ORMPostgreSQLAuth.jsASP.NET CoreFastAPIDocker
Deep Learning & Data
PyTorchTensorFlowMONAIScikit-learnNumPyPandasOpenCV
Programming
PythonC#.NETMATLABRGitSQL
Languages
🇨🇳 Mandarin: Native 🇬🇧 English: Proficient 🇯🇵 Japanese: Conversational 🇫🇷 French: Beginner
My Path

Career Journey

It started in a microfluidics lab in Shantou, led me to imaging research in Manchester, and from there into building AI products end to end. Here is how it unfolded.

01.2025 – Present
Independent AI / ML Developer
Self-employed
Shipping AI applications end to end for small businesses, from the model to a deployed product.
Designing and shipping AI applications end to end for small businesses, taking each one from the model through to a deployed product. Most of my recent work has been on tool-calling agents and on how you actually measure whether one is any good.
  • Built RadReport Agent, a tool-calling clinical imaging agent that chooses its own tools across a chest X-ray classifier, lung segmentation, cardiothoracic ratio geometry, report retrieval and PubMed, then answers with every claim checked against the raw tool output. Scored 97.7% tool selection and 96% groundedness on a 43-case gold set.
  • Built PantryChef, a Next.js/TypeScript recipe app with RAG-based chat (embedding index + cosine retrieval), integrating three external APIs and a Nutri-Score health grading layer; deployed to production with automated tests.
  • Built Chouette, a French-shadowing app pairing synced YouTube transcript playback with bring-your-own-key AI conversation practice, backed by Auth.js, Drizzle ORM and Postgres.
  • Built a full-stack medical image analysis platform (React, ASP.NET Core, FastAPI) running pretrained MONAI segmentation models on uploaded CT scans, with JWT auth and an interactive 3D viewer.
  • Shipped NoteWidget, a native macOS always-on-top sticky-note widget in SwiftUI/AppKit with a global hotkey, tagging and local SwiftData storage.
Tool-Calling AgentsNext.jsRAGASP.NET CoreMONAISwiftUICI/CD
09.2024 – 12.2024
Research Intern, Microfluidics & Genomics
BGI Research, National Gene Bank, Shenzhen
Four months hands-on with cell culture, single-cell library prep and PDMS chip fabrication.
An intensive four-month immersion at one of China's leading genomics institutes. Worked hands-on across four areas: cell culture and droplet generation for microfluidic experiments; C4 scRNA-seq V2 single-cell library preparation; fabrication and calibration of PDMS microfluidic chips; and barcode modification of magnetic beads using multi-channel pipettes. Coordinated daily with three other lab teams (wet-lab, chip fabrication and QC) to hand off samples and align on protocol changes, which meant a lot of cross-team communication to keep experiments from stalling. Gained fluency with electron microscopes, plasma cleaners, sorter machines and vacuum equipment. Learned to read experimental proposals independently and iterate when experiments failed.
MicrofluidicsSingle-cell SequencingPDMS Chip FabricationCell CultureDroplet GenerationElectron MicroscopyCross-team Collaboration
09.2023 – 09.2024
MSc Medical Imaging Science
University of Manchester, UK · Merit (2:1)
A year spent diving deep into CT and MRI analysis, imaging mathematics and computational methods. My dissertation focused on 3D vertebral shape modelling from CT scans, where I worked on landmark annotation and compared different model configurations for anatomical localisation.
CT ImagingMRIShape ModellingPython
03.2022 – 03.2023
Research Assistant, Microfluidics Laboratory
Shantou University
My first real taste of lab research, working on a microfluidic chip designed to detect lead ions in water. I ran the chip testing, managed the fluid control experiments and helped analyse performance data. We got reliable detection down to 0.1 ppm, which felt like a genuine win.
MicrofluidicsLab ResearchData Analysis
09.2019 – 06.2023
BEng (Hons) Biomedical Engineering
Shantou University, China · GPA 3.4/5.0 · Ranked Top 30%
Four years building the foundations in medical imaging physics, computational simulation and bioinformatics. Graduated with an average of 84/100 and a real curiosity for how engineering and medicine could work together.
Biomedical EngineeringMATLABMedical Physics
What I've Built

Project Highlights

The five projects that best show where I am now: a tool-calling clinical agent and full-stack AI builds, alongside medical imaging and deep learning work. Five more from my biomedical engineering background and other builds are one click away.

Latest Project
Live Demo
🤖
RadReport Agent: Tool-Calling Clinical Imaging Agent
Aug 2026
Give it a chest X-ray and a question, and it works out which tools to call.
Give it a chest X-ray and a question, and the agent works out which tools to call. It has six: a DenseNet-121 classifier, PSPNet lung and heart segmentation, deterministic cardiothoracic ratio geometry, BM25 report retrieval, exact case lookup and PubMed search. What comes back is a structured, cited answer where every clinical statement traces to the tool call that produced it. It is a research prototype built on the public, de-identified Indiana University chest X-ray collection, and it is not a medical device.
  • Built the agent loop over six tools with a handle-passing design: segmentation writes masks to disk and returns a handle the CTR tool consumes, so large arrays never enter the model’s context
  • Enforced grounding with Pydantic-validated structured output plus a verifier that checks every quote against raw tool output and rejects fabricated ones, which took groundedness from 52.9% to 96.0%
  • Wrote a 43-case gold-set evaluation harness with per-category scoring: 100% convergence, 97.7% tool-selection accuracy, $0.00102 and 11.7s median per query
  • Shipped a Streamlit UI with a live trace panel showing every tool call, its arguments, latency and returned JSON, plus one-click adversarial cases for missing data, out-of-scope requests and fabrication bait
  • Containerised the stack and verified it properly: 161 tests pass inside the image with --network none, which surfaced three defects the host suite could not
  • Deployed to a ~1 GB free tier by serving precomputed real model outputs behind a demo flag, cutting peak memory from 1,816 MB to 71 MB while retrieval and the agent loop stay fully live
PythonTool CallingAgent EvaluationPyTorchPydanticBM25 RetrievalStreamlitDocker
Personal Project
🩻
Medical Image Analysis Platform
Jul – Aug 2026
Upload a CT scan, run AI segmentation on it, and explore the result in 3D in the browser.
A full-stack demo platform for uploading CT scans (NIfTI format), running an AI segmentation model on them, and viewing the results in an interactive 3D viewer in the browser. An educational/portfolio project, clearly scoped as research-grade and not validated for clinical use.
  • Built a three-tier stack: React/Vite frontend, ASP.NET Core API for auth and orchestration, Python FastAPI service for inference, with PostgreSQL for metadata via EF Core
  • Integrated two pretrained MONAI Model Zoo bundles, a 3D UNet for spleen and a SegResNet trained on 104 structures for liver, kidneys, gallbladder, stomach, pancreas and bladder
  • Implemented JWT-based auth, NIfTI upload, and volume visualisation with segmentation overlays via Niivue
  • Surfaced segmentation stats (voxel count, estimated volume in mL, inference time, model used) and containerised the whole stack with Docker Compose
ReactASP.NET CoreFastAPIMONAIPostgreSQLDocker
View on GitHub
Personal Project
🍳
PantryChef: AI Recipe & Nutrition Assistant
Jun – Jul 2026
Turns whatever is in your kitchen into matching recipes, a health grade and a grounded Q&A assistant.
Built a full-stack app that turns whatever's in your kitchen into matching recipes and cooking videos, complete with a Nutri-Score-style health grade and a RAG-powered Q&A assistant grounded in a hand-curated meal-prep and nutrition knowledge base.
  • Built a retrieval-augmented generation pipeline (embeddings + cosine similarity search) grounding an LLM chat in a custom nutrition knowledge base, with cited sources
  • Implemented an explainable A–E health score by adapting the Nutri-Score formula to each recipe's nutrition facts
  • Integrated Spoonacular, YouTube Data API and Open Food Facts, with aggressive caching so the app degrades gracefully under tight free-tier quotas
  • Designed a pluggable LLM provider layer (Groq / Anthropic / OpenAI) so a public demo link never runs up someone else's API bill
Next.jsTypeScriptVercel AI SDKRAGTailwind CSS
View on GitHub
Master's Project
🦴
3D Vertebral Shape Modelling from CT
May 2024 – Sep 2024
Locating vertebrae in CT scans with landmark annotation and statistical 3D shape modelling.
Built a pipeline to localise vertebrae in CT scans using landmark annotation and statistical 3D shape modelling. A detail-heavy project that taught me a lot about the gap between a working model and a reproducible one.
  • Reviewed and refined 345 vertebral landmark annotations to improve training data quality
  • Compared single-stage vs two-stage configurations on localisation accuracy and runtime
  • Wrote up the full workflow so others could actually reproduce it
Statistical Shape ModellingCT AnalysisPython3D Reconstruction
View on GitHub
Bachelor's Project
🧠
Automated Intracranial Haemorrhage Segmentation
Jul 2022 – May 2023
Three segmentation models compared on 200 head CT volumes, tuned for small lesions.
Developed and evaluated three segmentation models — a 3D U-Net baseline plus improved 3D and 2D variants — on 200 non-contrast head CT volumes with voxel-level expert annotations, with preprocessing targeted at small-lesion performance.
  • Built brain-ROI extraction, HU windowing, median-spacing resampling and elastic/affine augmentation into the preprocessing pipeline
  • Raised mean Dice from 0.60 to 0.66 (3D) and 0.68 (2D), and cut Hausdorff Distance from 50.0 to 29.4
  • Configured the CUDA 11.0 / PyTorch 1.7 environment from scratch on a remote Linux workstation (SSH, single RTX 3080) within a 10 GB VRAM budget
PyTorchLinuxCUDA3D U-NetImage Segmentation
View on GitHub
Beyond the Lab

My Interests

What I get up to when I'm away from the keyboard.

🧗
Rock Climbing
Climbing is my favourite way to switch off. There is something I love about how it forces you to be fully present, physically and mentally. Every route is a puzzle and I am hooked.
📸 @joyn_n.climbs
✈️
Solo Travel
Last year I travelled solo across several countries and wrote up guides to help others do the same. Going alone sounds intimidating but it is honestly the best way to actually experience a place.
📕 My Travel Guides on Rednote
🇫🇷
Learning French
I'm working my way through French at the moment. I couldn't find a shadowing tool that did what I wanted, so I built one and now I use it most days.
🦉 Chouette, the app I built for it
What's Next

Next Destination

I am looking for a role where I can contribute from day one and keep growing. If you're building AI-powered products and think we might be a good fit, I would love to hear from you.

Roles I'm Open To
🤖
AI Engineer / ML Engineer
Building and shipping AI-powered products end to end, from RAG pipelines and LLM integration to production deployment.
💻
Full-Stack AI Developer
Next.js, TypeScript and the Vercel AI SDK, turning an idea into a deployed, working product fast.
🧠
Applied AI, Healthcare & Life Sciences
Bringing deep learning experience from medical imaging (segmentation, 3D shape modelling) into AI systems that matter in healthcare.
Available Now · UK-based · No Sponsorship Required
Say hello
Send me a message