Personalized Biological Engineering Heart Toddler T-Shirt. Biological engineering text in a heart with pimples is a humorous design for bioengineers. Fun gift ideas for birthdays, holidays, graduation and Valentine's Day. A toddler-soft cotton tee in look-at-me, big kid colors. 4.5 oz., 100% combed ringspun cotton. White is sewn with 100% cotton thread. Topstitched rib crew neck. Double-needle stitched sleeves and bottom hem. Shoulder-to-shoulder taping.